JP2011506040A - System and method for manufacturing an arthroplasty jig - Google Patents

Abstract

  A method for generating a three-dimensional surface model of a joint arthroplasty target site of a bone forming a joint is disclosed. The method includes generating a two-dimensional image of at least a portion of a bone, generating an open-loop contour along an arthroplasty site in at least some of the two-dimensional images, Generating a three-dimensional model of the target site for arthroplasty from the contour line.

Description

  The present invention relates to a system and method for producing specialized arthroplasty cutting jigs. More particularly, the present invention relates to a system and method for automatically manufacturing such jigs.

  Over time and repeated use, bones and joints can be damaged or worn. For example, repeated loads on bones and joints (eg, due to exercise), trauma accidents, and certain illnesses (eg, arthritis) can wear the cartilage in the joint area, which usually provides a cushioning effect. When cartilage wears, fluid accumulates in the joints, causing pain, stiffness, and decreased motor function.

  Arthroplasty procedures may be performed to repair damaged joints. In normal arthroplasty procedures, arthritic or otherwise dysfunctional joints may be remodeled, ie readjusted, or an implant may be implanted at the site of injury. The arthroplasty procedure can be performed on any of various parts of the body, such as the knees, hips, shoulders, or elbows.

  One arthroplasty procedure is artificial knee arthroplasty (“TKA”), which replaces a damaged knee joint with an artificial implant. The knee joint may have been damaged, for example, by arthritis (eg, severe osteoarthritis or degenerative arthritis), trauma, or rare destructive arthropathy. In TKA procedures, the distal part of the femur is removed and replaced with a metal shell, the damaged part of the proximal part of the tibia is removed, and a channeled plastic with a metal trunk It may be replaced with a piece. In some TKA procedures, a plastic button may be added below the curved surface of the patella, depending on the condition of the patella.

  Implants implanted at the injury site can support the injury site, form tissue, and help restore the injury site, thereby enhancing functionality. Prior to implanting the implant at the damaged site, the damaged site may be adjusted to accept the implant. For example, in knee arthroplasty procedures, one or more bones in the knee region, such as the femur and / or tibia, are treated (eg, cut, drilling, reaming, and / or resurfacing). Thus, one or more surfaces may be aligned with the implant so that the implant is received.

  Implant alignment accuracy is an important factor for successful TKA procedures. A translational misalignment of 1,2 millimeters, or a rotational misalignment of 1,2 degrees can cause the ligament to become unbalanced, thereby significantly affecting the outcome of the TKA procedure. For example, implant mismatch can cause unbearable postoperative pain, and the patient may not be able to stretch their legs completely and stably.

  Prior to treating any part of the bone (eg, cutting, drilling, drilling, and / or resurfacing) to ensure correct implant alignment, the exact location and direction of treatment should be determined. It is important to decide. In some methods, an arthroplasty jig is used to place a finishing device, such as a cutting, drilling, punching, or resurfacing device, in the correct position and orientation relative to the bone site. May be used. An arthroplasty jig may include, for example, one or more openings and / or slots configured to receive these instruments.

  Specialized arthroplasty configured to allow surgeons to accurately and quickly perform arthroplasty procedures that restore joint alignment before degeneration, thereby improving the success rate of such procedures Systems and methods for manufacturing jigs have been developed. In particular, specialized arthroplasty jigs are indexed to matingly receive the site of the bone to be treated (eg, cutting, drilling, drilling and / or resurfacing). Specialized arthroplasty jigs are also indexed to give the exact location and orientation of treatment to the bone site. By indexing specialized arthroplasty jigs, bone sites can be treated quickly and with a high degree of accuracy that allows the implant to restore the patient's joints to their pre-degenerative state. However, systems and methods for generating specialized jigs often rely on a human gaze at a bone model on a computer screen to measure the shape required to generate the specialized jig. It is inefficient to stare at the bone model on the computer screen, that is, to manually manipulate it, which creates unnecessary time, resources and costs associated with producing specialized arthroplasty jigs. To do. Furthermore, the accuracy of the obtained jig can be improved by reducing the degree of manual operation.

  There is a need in the art for systems and methods that reduce the effort associated with generating specialized arthroplasty jigs. Furthermore, there is a need in the art for systems and methods that improve the accuracy of specialized arthroplasty jigs.

  The present application discloses a method of manufacturing an arthroplasty jig. In one embodiment, a method generates a two-dimensional image of at least a portion of a bone forming a joint, and generates a first three-dimensional computer model of at least a portion of the bone from the two-dimensional image. A step of generating a second 3D computer model of at least a part of the bone from the 2D image, and the first 3D computer model and the second 3D computer model Generating a first type data using a step including at least one of a position and a direction with respect to the origin, and the first three-dimensional computer model. A step of generating second type data using the second three-dimensional computer model, and the first type data and the second using the reference position. Comprising a step of integrating the Ipudeta integration jig data, by using the integrated jig data, the steps of manufacturing the arthroplasty jigs in the production machine, the.

  The present application discloses a method of manufacturing an arthroplasty jig. In one embodiment, a method generates a two-dimensional image of at least a portion of a bone forming a joint, and at least some of the two-dimensional images include an open-loop contour along an arthroplasty target site. A step of extending a line, a step of generating a three-dimensional computer model of the arthroplasty target region from the open loop contour line, and a step of generating curved surface contour data of the joint plastic surgery target region from the three-dimensional computer model And manufacturing the arthroplasty jig with a manufacturing machine using the curved surface contour data.

  The present application discloses a method of manufacturing an arthroplasty jig. In one embodiment, the method includes measuring at least one dimension associated with a portion of the bone from the image, the at least one dimension, and at least two candidate jig blank sizes. A step of comparing, a step of selecting a smallest jig blank size capable of accommodating the at least one dimension, a step of supplying a jig blank of the selected size to a manufacturing machine, and the jig blank from the jig blank Manufacturing an arthroplasty jig.

  The present application discloses an arthroplasty jig manufactured by any of the foregoing manufacturing methods. In some embodiments, the arthroplasty jig may be indexed to capture the arthroplasty site of the articular bone. The arthroplasty jig also includes saw cutting and drilling performed on the arthroplasty target site via the saw cutting slot and drill hole guide when the arthroplasty target site is captured by the arthroplasty jig. To facilitate the arthroplasty implant to roughly restore the joint to its pre-degenerative state, the arthroplasty jig may be indexed to face the sawing slot and the drill hole guide.

  The present application discloses a method of computer-generating a three-dimensional surface model of a joint arthroplasty target site forming a joint. In one embodiment, the method includes generating a two-dimensional image of at least a portion of the bone, and providing an open loop contour along the arthroplasty target site in at least some of the two-dimensional images. And generating a three-dimensional model of the arthroplasty site from the open loop contour.

  The present application discloses a method for generating a three-dimensional arthroplasty jig computer model. In one embodiment, the method includes comparing the dimensions of at least a portion of the bone of the joint with the dimensions of the candidate jig blank size, and receiving at least a dimension of the bone from the candidate jig blank size. Selecting the smallest jig blank size that can be.

  The present application discloses a method for generating a three-dimensional arthroplasty jig computer model. In one embodiment, the method includes forming an inner 3D surface model that represents at least a portion of the bone to be arthroplasty and forming an outer 3D surface model that represents the outer surface of the jig blank. And combining the inner surface model and the outer surface model to form an inner surface and an outer surface of the three-dimensional arthroplasty jig computer model, respectively.

  The present application discloses a method for generating a production file related to the manufacture of an arthroplasty jig. The method includes the steps of generating first data related to a curved contour of an arthroplasty site of a joint bone, and at least a saw cutting portion and a drill hole applied to the arthroplasty site in the course of arthroplasty treatment. A step of generating second data related to one; and a step of integrating the first data and the second data, the positional relationship of the first data with respect to the origin, and the second data with respect to the origin Are adjusted during the generation of each of the first data and the second data so that their positional relations substantially coincide with each other.

  While several embodiments have been disclosed, other embodiments of the invention will be apparent to those skilled in the art upon reading the following detailed description, which illustrates and describes the illustrative embodiments of the invention. As will be apparent, various modifications of the invention can be made without departing from the spirit and scope of the invention. Accordingly, the drawings and detailed description herein are illustrative in nature and not restrictive.

It is the schematic of the system using the automatic jig production method disclosed by this application. It is a flowchart which shows the outline | summary of the automatic jig production method disclosed by this application. It is a flowchart which shows the outline | summary of the automatic jig production method disclosed by this application. It is a flowchart which shows the outline | summary of the automatic jig production method disclosed by this application. It is a flowchart which shows the outline | summary of the automatic jig production method disclosed by this application. FIG. 6 is a bottom perspective view of an exemplary specialized arthroplasty femur jig. 3 is a top perspective view of an exemplary specialized arthroplasty femur jig. FIG. FIG. 6 is a bottom perspective view of an exemplary specialized arthroplasty tibial jig. 3 is a top perspective view of an exemplary specialized arthroplasty tibial jig. FIG. FIG. 6 is an anterior-posterior image slice of a damaged lower end of a patient's femur, ie, a knee joint end, including an open loop contour corresponding to a target site of the damaged lower end. FIG. 5 is a plurality of image slices each having an open loop contour segment accumulated to generate a 3D model of a target region. FIG. 2D is a 3D model of a damaged lower end target site generated using the open loop contour segment shown in FIG. 2B. FIG. 6 is a damaged lower end of a patient's femur, ie, an anterior-posterior image slice of the knee joint end, including a closed loop contour corresponding to the lower femur end including the site of interest. FIG. 6 is a plurality of image slices each having a closed loop contour segment accumulated to generate a 3D model of the lower femur end including the region of interest. FIG. FIG. 2D is a 3D model of the lower femur end including the site of interest generated using the closed loop contour shown in FIG. 2E. It is a flowchart which shows the outline | summary of the method of manufacturing a femur jig. It is a top perspective view of the left femur cutting jig material having a predetermined dimension. It is a bottom perspective view of the jig material shown in FIG. 3A. FIG. 3B is a plan view of the outside of the jig material shown in FIG. FIG. 3D is a diagram showing a plurality of available sizes of left femur jig blank shown respectively by the plan view shown in FIG. 3C. FIG. 3D is a diagram illustrating a plurality of available sizes of the right femur jig blank shown respectively by the plan view shown in FIG. 3C. FIG. 3 is an axis view of a 3D surface model, or joint model, of a patient's left femur viewed from the distal to the proximal direction. FIG. 6 shows the selected model jig blank of FIG. 3C superimposed on the lower model femur lower end of FIG. It is a figure which shows the example scatter diagram for selecting the jig raw material size suitable for the lower end of a patient's femur from several candidate jig raw material size. It is a flowchart which shows the Example of the process which selects the jig material of a suitable size. It is an outer side perspective view of a femur jig raw material outer surface model. FIG. 8B is a medial perspective view of the femur jig blank outer surface model of FIG. 8A. FIG. 5 is a perspective view of an extracted jig blank outer surface model that is about to be combined with an extracted femur surface model. FIG. 6 is a perspective view of an extracted jig blank outer surface model combined with an extracted femur surface model. It is sectional drawing seen along the cutting | disconnection line CC of FIG. 9B with the combined jig raw material outer surface model and femur surface model. It is an outer side perspective view of the obtained femur jig model. FIG. 10B is a medial perspective view of the femur jig model of FIG. 10A. It is a perspective view of an integrated jig model mated with a “joint model”. An anterior-posterior image slice of the damaged upper end of the patient's tibia, ie, the end of the knee joint. FIG. 5 is a plurality of image slices each having an open loop contour segment accumulated to generate a 3D model of the region of interest. FIG. FIG. 12C shows a 3D model of a damaged upper end region of interest generated using the open loop contour segment shown in FIG. 12B. FIG. 6 is a top perspective view of a right tibial cutting jig blank having a predetermined dimension. FIG. 13B is a bottom perspective view of the jig material shown in FIG. 13A. It is the top view of the outer side, ie, an outer side part, of the jig blank 50BR shown to FIG. 13A. FIG. 13C is a diagram illustrating a plurality of available sizes of the right tibial jig blank shown by the plan view shown in FIG. 13C. FIG. 3 is an axis view of a 3D surface model, or joint model, of a patient's right tibia as viewed from the proximal to the distal direction. FIG. 16 shows the selected model jig blank of FIG. 13C superimposed on the model tibia upper end of FIG. It is a figure which shows the example scatter diagram for selecting the jig raw material size suitable for the upper end of a patient's tibia from several candidate jig raw material size. It is a flowchart which shows the Example of the process which selects the jig material of a suitable size. It is an outer side perspective view of a tibial jig raw material outer surface model. FIG. 18B is a medial perspective view of the tibial jig blank outer surface model of FIG. 18A. FIG. 6 is a perspective view of an extracted jig blank outer surface model that is about to be combined with an extracted tibial surface model. FIG. 6 is a perspective view of an extracted jig blank outer surface model combined with an extracted tibial surface model. FIG. 6 is a perspective view of an extracted jig blank outer surface model combined with an extracted tibial surface model. FIG. 6 is a perspective view of an extracted jig blank outer surface model combined with an extracted tibial surface model. It is an outer side perspective view of the obtained tibial jig model. FIG. 20B is a medial perspective view of the tibial jig model of FIG. 20A. It is a perspective view of an integrated jig model mated with a “joint model”.

The present application discloses specialized arthroplasty jigs 2 and systems 4 and methods for producing such jigs 2. The jig 2 is specialized to fit a specific bone curved surface of a specific patient. Depending on the embodiment and more or less, the jig 2 is automatically designed and generated and is similar to that disclosed in the following three US patent applications.
US Patent Application No. 11 / 656,323, Park et al., Arthroplasty Devices and Related Methods, filed Jan. 19, 2007 US Patent Application No. 10 / 146,862, Park et al., Improved Total Joint Arthroplasty System, 2002 5 Filed on May 15 US Patent Application No. 11 / 642,385, Park et al., Arthroplasty Devices and Related Methods, filed December 19, 2006 The disclosure of these three US patent applications is hereby incorporated by reference in its entirety. Is done.

  a. Overview of systems and methods for manufacturing specialized arthroplasty cutting jigs

  An overview of a system 4 and method for manufacturing a specialized arthroplasty jig 2 will be described with reference to FIGS. FIG. 1A is a schematic diagram of a system 4 that uses the automated jig manufacturing method disclosed by the present application. 1B to 1E are flowcharts showing an outline of a jig manufacturing method disclosed by the present application. The following summary description is divided into three sections.

  The first section is described with respect to blocks 100-125 of FIGS. 1A and 1B-1E, and in a three-dimensional (3D) computer model environment, for a 3D computer model referred to as a restored bone model 28, a saw cutting position 30 and The present invention relates to an exemplary method for determining the drilling position 32. The resulting “saw cutting and drilling data” 44 is referenced to the restored bone model 28 to perform saw cutting and drilling to allow an arthroplasty implant to restore the patient's joint to its pre-degenerative state.

  The second section is described with respect to blocks 100-105 and 130-145 of FIGS. 1A and 1B-1E, and includes the 3D computer generated jig model 38 in the arthroplasty area of the 3D computer generated joint model 36 of the patient's joint bone. It relates to an exemplary method for capturing 42 3D computer generated surface models 40. The resulting “jig data” 46 is used to produce a specialized jig to capture the arthroplasty target area of the corresponding bone of the patient's joint.

  The third section is described with respect to blocks 150-165 of FIGS. 1A and 1E and relates to a method of combining “saw cutting and drilling data” 44 with “jig data” 46, ie, integrating to obtain “integrated jig data” 48. . The “integrated jig data” 48 is supplied to the CNC machine 10 in order to manufacture the specialized arthroplasty jig 2 from the jig material 50 supplied to the CNC machine 10. The resulting specialized arthroplasty jig 2 includes a sawing slot and a drill hole located in the jig 2, and when the jig 2 captures the arthroplasty area of the patient's bone, the arthroplasty joint implant is the patient The cutting slot and the drill hole make it easy to adjust the arthroplasty target area so that the joint line can be roughly restored to the state before degeneration.

  As shown in FIG. 1A, the system 4 includes a computer 6 having a CPU 8, a monitor, that is, a screen 9, and an operator interface control unit 11. The computer 6 is connected to a medical imaging system 8 such as a CT or MRI apparatus 8 and a computer controlled machining system 10 such as a CNC milling machine 10.

  As shown in FIG. 1A, patient 12 has replacement joints 14 (eg, knees, elbows, feet, hands, hips, shoulders, skull / spine or spine / spine interface, etc.). The patient 12 is scanned through the joint 14 by the imaging device 8. The imaging device 8 creates a plurality of scan data for the joint 14, and each scan data represents a thin slice of the joint 14.

  As can be seen from FIG. 1B, the plurality of scan data is used to generate a plurality of two-dimensional (2D) images 16 of the joint 14 (block 100). Here, for example, the joint 14 is the knee 14, and the 2D image is of the femur 18 and the tibia 20. Imaging can be done with CT or MRI. In one embodiment using MRI, the imaging process is described in US Patent Application No. 11 / 946,002 to Park, Generating MRI Images Usable For The Creation Of 3D Bone Models Employed to Make Customized Arthroplasty Jigs, November 27, 2007. As disclosed in Japanese Patent Application, which is hereby incorporated by reference in its entirety.

  As can be seen from FIG. 1A, the 2D image is transmitted to the computer 6 to generate a computer generated 3D model. As shown in FIG. 1B, in one embodiment, the point P is identified in the 2D image 16 (block 105). In one embodiment, as shown in block 105 of FIG. 1A, the point P may be approximately the center of the medial-lateral and anterior-posterior surface of the patient's joint 14. In another embodiment, point P may be at any other location in 2D image 16 that includes any point on, near, or far from bone 14, 20 or joint 14 formed by bone 18, 20. There may be.

  As will be described later in this overview, the computer-generated 3D models 22, 28, and 36 generated from the 2D image 16 using the point P can be found, and the information generated by the 3D model can be integrated. Depending on the embodiment, the point P, which serves as a reference destination for the point and / or the origin, is used to position and / or define the 3D model 22, 28, 36 generated by the 2D image 16. Can be single points, two points, three points, points and planes, vectors, etc.

As shown in FIG. 1C, the 2D image 16 may be used to generate a computer generated 3D bone model (or “bone model”) 22 of the bones 18 and 20 that form the patient's joint 14 (block 110). The bone model 22 is such that the point P is located at coordinates (X _0-j , Y _0-j , Z _0-j ) with respect to the origin (X ₀ , Y ₀ , Z ₀ ) of the XYZ axis. Placed in. (Block 110). The bone model 22 represents the current degraded bone 18, 20 with corresponding degenerative joint surfaces 24, 26 that may be the result of osteoarthritis, injury, their complications, and the like.

  The computer program for generating the 3D computer generated bone model 22 from the 2D image 16 includes the following. From Insight Toolkit, www.slicer.org, open source software available from Overland Park, KS, AnalyzeDirect, Inc. Analyze, National Library of Medicine Insight Segmentation and Registration Toolkit ("ITK"), www.itk.org Paraview can be obtained from 3D Slicer, Ann Arbor, MI's Mimics from Matelialise, www.paraview.org.

As shown in FIG. 1C, a 3D computer-generated “restored bone model” or “planned bone model” 28 can be generated using the 3D computer-generated bone model 22, and the modified curved surfaces 24 and 26 are approximately modified. It is modified or restored to its previous respective state (block 115). In this way, the bones 18 and 20 of the restored bone model 28 have the point P at the coordinates (X _0-j , Y _0-j , Z _0-j ) with respect to the origin (X ₀ , Y ₀ , Z ₀ ). It is arranged to be located. Thus, the restored bone model 28 shares the same direction and position as the bone model 22 with respect to the origin (X ₀ , Y ₀ , Z ₀ ).

  In one embodiment, the reconstructed bone model 28 is obtained by a person sitting in front of the computer 6 and visually observing the bone model 22 and its modified curved surfaces 24 and 26 as a 3D computer model on the computer screen 9. Manually generated from the bone model 22. The person needs to modify the modified curved surfaces 24 and 26 of the 3D bone model 22 in order to restore the state before the modified curved surfaces 24 and 26 are visually observed. Determine whether. The person interacts with the computer control unit 11 to manually operate the 3D modified curved surfaces 24 and 26 by the 3D modeling computer program, and restores the curved surface to a state that the person believes represents the state before the modification. To do. The result of this manual restoration processing is a computer-generated 3D restoration bone model 28, and the curved surfaces 24 'and 26' represent a non-denaturing state.

  In one embodiment, the above bone restoration process is outlined or fully automated. In other words, the computer program analyzes the bone model 22 and the modified curved surfaces 24 and 26, and how and how the modified curved surfaces 24 and 26 of the 3D bone model 22 are restored in order to restore the state before the modification. Determine whether it is necessary to correct the degree. Then, the computer program operates the 3D modified curved surfaces 24 and 26 to restore the curved surfaces 24 and 26 to a state representing the state before the modification. The result of this automatic restoration processing is a computer-generated 3D restoration bone model 28, and the curved surfaces 24 'and 26' represent a non-denaturing state.

  As shown in FIG. 1C, the restored bone model 28 is used in a preoperative planning (“POP”) procedure so that the arthroplasty joint implant can roughly restore the patient's joint line to its pre-degenerative state. A bone sawing position 30 and a drilling position 32 are determined (block 120).

  In one embodiment, the POP procedure is a manual process, in which a person sits in front of the computer 6 and visually observes the implant model 34 and the restored bone model 28 on the computer screen 9, and the computer control unit 11 uses the model 28, By manipulating 34, a computer generated 3D implant model 34 (eg, femoral and tibia implants when the joint is a knee) and a restored bone model 28 are manually manipulated with respect to each other. By superimposing the implant model 34 on the restored bone model 28 or vice versa, the joint surface of the implant model 34 can be aligned, that is, can correspond to the joint surface of the restored bone model 28. By aligning the articulating surfaces of the models 28, 34 so, the implant model 34 is positioned relative to the restored bone model 28 so that the sawing position 30 and the drilling position 32 can be determined relative to the restored bone model 28. The

In one embodiment, the POP process is outlined or fully automated. For example, a computer program interacts with a computer-generated 3D implant model 34 (eg, femoral and tibia implants when the joint is a knee) and a reconstructed or planned bone model 28 to produce a sawing position 30 and drilling. A position 32 is determined with respect to the restored bone model 28. The implant model 34 may be superimposed on the restored bone model 28 and vice versa. In one embodiment, the implant model 34 is located at the point P ′ (X _0−k , Y _0−k , Z _0−k ) and restored relative to the origin (X ₀ , Y ₀ , Z ₀ ). The bone model 28 is arranged at the point P (X _0-j , Y _0-j , Z _0-j ). In order to make the joint surfaces of the models 28 and 34 correspond, the computer program changes the restored bone model 28 from the point P (X _{0 -j} , Y _{0 -j} , Z _{0 -j} ) to the point P ′ (X _{0 -k} , Y _{0). -K} , _{Z0 -k} ) or vice versa. When the joint surfaces of the models 28 and 34 are close to each other, the joint surface of the implant model 34 is aligned with the joint surface of the restored bone model 28, that is, is matched. By aligning the articulating surfaces of the models 28, 34 so, the implant model 34 is positioned relative to the restored bone model 28 so that the sawing position 30 and the drilling position 32 can be determined relative to the restored bone model 28. The

As shown in FIG. 1E, in one embodiment, data 44 relating to the saw cutting position 30 and the drilling position 32 for point P ′ (X _0-k , Y _0-k , Z _0-k ) is “saw cutting and Packaged or merged as “drilling data” 44 (block 145). The “saw cutting and drilling data” 44 is then utilized as described below with respect to block 150 of FIG. 1E.

As can be seen from FIG. 1D, the 2D image 16 used to generate the bone model 22 described above with respect to block 110 of FIG. 1C is a computer generated 3D bone and cartilage model of bones 18, 20 forming the patient's joint 14 ( That is, it is also used to generate a “joint model”) 36 (block 130). Similar to the bone model 22 described above, the joint model 36 has coordinates (X _0-j , Y _0-j , Z) where the point P is relative to the origin (X ₀ , Y ₀ , Z ₀ ) of the XYZ axis. _0-j ) (block 130). In this way, the bone model 22 and the joint model 36 share the same position and direction with respect to the origin (X ₀ , Y ₀ , Z ₀ ). This position / orientation relationship is generally maintained through the process described with respect to FIGS. Thus, the movement of the bone model 22 and its various descendants (ie, the restored bone model 28, the bone cutting position 30 and the drill hole position 32) relative to the origin (X ₀ , Y ₀ , Z ₀ ) is also Applies to model 36 and its various subgroups (ie, jig model 38). By maintaining the position / orientation relationship between the bone model 22 and the joint model 36 and their respective subgroups, the “saw cutting and drilling data” 44 integrated into the “jig data” 46 is a specialized arthroplasty jig. The “integrated jig data” 48 used by the CNC machine 10 to produce 2 is formed.

  The computer program for generating the 3D computer generated joint model 36 from the 2D image 16 includes the following. From Insight Toolkit, www.slicer.org, open source software available from Overland Park, KS, AnalyzeDirect, Inc. Analyze, National Library of Medicine Insight Segmentation and Registration Toolkit ("ITK"), www.itk.org Paraview can be obtained from 3D Slicer, Ann Arbor, MI's Mimics from Matelialise, www.paraview.org.

  Similar to the bone model 22, the joint model 36 replaces the current degraded bones 18, 20 with the corresponding degenerative joint surfaces that may be the result of osteoarthritis, injury, their complications, etc. Expressed with 24 and 26. However, unlike the bone model 22, the joint model 36 is not a single bone model but includes cartilage in addition to bone. Accordingly, the joint model 36 represents the arthroplasty target region 42 where the joint model will generally exist when the specialized arthroplasty jig 2 captures the arthroplasty target region 42 in the arthroplasty surgical procedure.

  As shown in FIG. 1D and as already described above, any movement of the restored bone model 28 from point P to point P ′ is tracked to adjust the position / direction of the bone model 22 and joint model 36 and their respective subgroups. , Approximately the same displacement is given to the “joint model” 36 (block 135).

  As shown in FIG. 1D, the computer generated 3D surface model 40 of the arthroplasty target area 42 of the joint model 36 is captured in the computer generated 3D arthroplasty jig model 38 (block 140). Thus, the jig model 38 is constructed, that is, an index is attached so as to capture the arthroplasty symmetry region 42 of the joint model 36. Therefore, the jig 2 manufactured so as to match the jig model 38 captures the actual arthroplasty target region of the articular bone in the arthroplasty surgical procedure.

In one embodiment, the procedure for indexing the jig model 38 to the arthroplasty target area 42 is a manual process. The 3D computer generation models 36 and 38 are obtained by observing the jig model 38 and the joint model 36 on the computer screen 9 with a person sitting in front of the computer 6 and interacting with the computer control unit 11. By operating, they are manually operated with each other. In one embodiment, a jig model 38 (eg, a femur and tibial arthroplasty jig when the joint is a knee) is superimposed on the arthroplasty area 42 of the joint model 36, or vice versa. The surface model 40 of the arthroplasty target area 42 can be taken into the jig model 38 and, as a result, the jig model 38 is indexed to capture the arthroplasty target area 42 of the joint model 36. The point P ′ (X _0-k , Y _0-k , Z _0-k ) can also be incorporated into the jig model 38, and as a result, the jig model 38 becomes the point P ′ (X _0-k , Y _0-k , Z _0-k ) so that it can be integrated with the sawing and drilling data 44 of the block 125.

In one embodiment, as described later in this specification, the procedure for indexing the jig model 38 into the arthroplasty target area 42 is generally or completely automated. For example, the computer program may generate the 3D computer generated surface model 40 of the arthroplasty target area 42 of the joint model 36. Then, the computer program loads the surface model 40 and the point P ′ (X _0-k , Y _0-k , Z _0-k ) into the jig model 38, and as a result, captures the arthroplasty target region 42 of the joint model 36. In this way, the jig model 38 may be indexed. Also, the resulting jig model 38 can be positioned and oriented relative to the point P ′ (X _0-k , Y _0-k , Z _0-k ) so that it can be integrated with the sawing and drilling data 44 of the block 125. Become.

  In one embodiment, the joint model 36 may be a 3D volume model generated by a closed loop process described below with respect to FIGS. In another embodiment, the joint model 36 may be a 3D surface model generated by an open loop process described below with respect to FIGS. 2A-2C and 12A-12C.

As shown in FIG. 1E, in one embodiment, data relating to the jig model 38 and the surface model 40 for the point P ′ (X _0-k , Y _0-k , Z _0-k ) is packaged as “jig data” 46. That is, they are merged (block 145). The “jig data” 46 is then used as described below with respect to block 150 of FIG. 1E.

  As can be seen from FIG. 1E, “saw cutting and drilling data” 44 is integrated into “jig data” 46 to become “integrated jig data” 48 (block 150). As described above, “saw cutting and drilling data” 44, “jig data” 46 and their various ancestors (eg, models 22, 28, 36, 38) are mutually connected with respect to points P and P ′. Since the position and orientation are aligned, the “saw cutting and drilling data” 44 is correctly aligned and oriented with respect to the “jig data” 46 and correctly integrated into the “jig data” 46. When the resulting “integrated jig data” 48 is supplied to the CNC machine 10, the jig 2 is configured to (1) capture the arthroplasty target area of the patient's bone, and (2) the arthroplasty joint implant It has cutting slots and drill holes that make it easy to adjust the arthroplasty target area so as to roughly restore the patient's joint line to its pre-degenerative state.

  As can be seen from FIGS. 1A and 1E, “integrated jig data” 48 is transferred from the computer 6 to the CNC machine 10 (block 155). The jig blank 50 is supplied to the CNC machine 10 (block 160), and the CNC machine 10 produces the arthroplasty jig 2 from the jig blank 50 using the “integrated jig data”.

  To illustrate an exemplary specialized arthroplasty cutting jig 2 manufactured by the process described above, reference is made to FIGS. As described above, the above-described process can be used to produce a jig 2 configured for arthroplasty procedures including knees, elbows, feet, hands, hips, shoulders, spinal joints, etc. The jig examples shown in FIGS. 1F-1I are for knee replacement (“TKR”) procedures. 1F and 1G are bottom and top perspective views of the exemplary specialized arthroplasty femur jig 2A, respectively, and FIGS. 1H and 1I are bottom and top perspective views of the exemplary specialized arthroplasty tibial jig 2B, respectively. It is.

  As shown in FIGS. 1F and 1G, the femoral arthroplasty jig 2A may include an inner or inner portion 100 and an outer or outer portion 102. When using the femur cutting jig 2A in a TKR procedure, the medial or medial portion 100 faces and captures the arthroplasty region 42 at the lower femur end. The outer side, i.e., the outer portion 102, is on the opposite side of the inner portion 100 of the femur cutting jig 2A.

  The inner portion 100 of the femur jig 2A is configured to match the curved features of the damaged lower end of the patient's femur 18 (ie, the arthroplasty subject area 42). Therefore, during the TKR operation, the target region 42 is captured by the inner portion 100 of the femur jig 2A, and the curved surface of the target region 42 matches the curved surface of the inner portion 100.

  The curved surface of the inner portion 100 of the femur cutting jig 2A is machined or otherwise fabricated from the selected femoral jig blank 50A and damaged target area 42 at the lower end, ie, the target area of the patient's femur 18 42 based on the 3D surface model 40, ie, defined by the surface model.

  As shown in FIGS. 1H and 1I, the tibial arthroplasty jig 2 </ b> B may include an inner or inner portion 104 and an outer or outer portion 106. When using the tibial cutting jig 2B in a TKR procedure, the medial or medial portion 104 faces and captures the arthroplasty region 42 at the upper tibia distal end. And the outer side, ie, the outer part 106, is opposite to the inner part 104 of the tibial cutting jig 2B.

  The inner portion 104 of the tibial jig 2B is configured to match the curved shape of the damaged upper end of the patient's tibia 20 (ie, the arthroplasty target region 42). Therefore, during the TKR operation, the target region 42 is captured by the inner portion 104 of the tibial jig 2B, and the curved surface of the target region 42 matches the curved surface of the inner portion 104.

  The curved surface of the inner portion 104 of the tibial cutting jig 2B is machined or otherwise fabricated from the selected tibial jig blank 50B to create a damaged upper end target area 42, ie, the target area 42 of the patient's tibia 20. It is based on the 3D surface model 40, i.e. defined by the surface model.

  b. Overview of automatic processing for indexing 3D arthroplasty jig models into arthroplasty target areas

  As described above with respect to block 140 of FIG. 1D, the process of indexing the 3D arthroplasty jig model 38 into the arthroplasty target area 42 can be automated. An example of such an automatic process begins with an overview of the automatic indexing process and is described in the remainder of this specification.

  As can be seen from blocks 100-105 in FIGS. 1A and 1B, patient 12 has a replacement joint 14 (eg, knee, elbow, foot, hand, shoulder, waist, spinal interface, etc.). A patient 12 scans a joint 14 with an imaging device 10 (eg, CT, MRI, etc.) and a 2D scanned image of bones (eg, femur 18 and tibia 20) forming the patient's joint 14 (eg, knee). 16 is generated. Each scanned image 16 is a thin slice image of the target bones 18 and 20. The scanned image 16 is transmitted to the CPU 8, and the CPU performs an open loop image analysis along the target shape 42 of the scanned image 16 of the bones 18 and 20, and for each scanned image 16 along the contour of the target shape 42. Generate contour lines.

  As can be seen from block 110 in FIGS. 1A and 1C, the CPU 8 collects the scanned image 16, more specifically the contour line, to form a 3D computer surface model of the shape 42 that is the subject of the patient's articular bones 18, 20 (“ Joint model ") 36 is generated. In the case of a knee replacement (“TKR”) procedure, the shapes 42 of interest are the lower end of the patient's femur 18, the knee joint end, and the patient's tibia 20 upper end, the knee joint end. Good. More specifically, the shape 42 of interest may be a joint surface that contacts the tibia of the patient's femur 18 and a joint surface that contacts the femur of the patient's tibia 20.

  In some embodiments, the “joint model” 36 may be a surface model or a volume solid model, and each model is formed by an open loop process or a closed loop process, respectively, such that the contour line is open loop or closed loop, respectively. Is done. In one embodiment described in detail herein, the “joint model” 36 may be a surface model formed by an open loop process. By using the open loop and surface model methods, the computer modeling process does not require much CPU 8 processing power and time, as a result, as opposed to the closed loop and volume solid model methods, and as a result is more cost effective.

  The system 4 measures the front-rear length and medial-lateral length of the target area 42 of the “joint model” 36. The anterior-posterior length and the medial-lateral length may be used to measure the aspect ratio, size and / or shape of the 3D “joint model” 36 of the corresponding bone 18,20. In one embodiment of the jig material grouping and selection method described below, the aspect ratio, size, and / or shape of the 3D “joint model” 36 of the corresponding bone 18, 20 is determined by the jig material grouping and You may use for the comparison with the aspect ratio, size, and / or shape of 3D computer model of candidate jig material 50 in a selection method. In one embodiment of the jig blank grouping and selection method described below, the anterior-posterior dimension and medial-lateral dimension of the 3D “joint model” 36 of the corresponding bone 18, 20 is represented by the 3D of the candidate jig blank 50. It may be used to compare the computer model's front-rear and inner-outer dimensions.

  In the case of TKR, the jig 2 is a femur and tibial arthroplasty cutting jig 2A, 2B, which is fabricated from the femur and tibial jig blanks 50A, 50B by machining or otherwise formed. A plurality of candidate jig material sizes exist in, for example, a jig material library. Each candidate jig blank may have a unique combination of front-rear dimension and inner-outer dimension, but in some embodiments, two or more candidate jig blanks have a common aspect ratio or The shape may be shared. The candidate jig materials in the library may be grouped along the diagonal lines of the scatter diagram according to the aspect ratio. The system 4 uses a jig material grouping and selection method to select a jig material 50 from a plurality of available jig material sizes included in the jig material library. For example, the shape, size, and / or aspect ratio of the tibia and femur 3D joint model 36 may be combined with the dimensional comparison between the joint model 36 and the candidate jig material model, or independently, the shape, size of the 3D model of the candidate jig material. And / or compared to the aspect ratio.

  Alternatively, in one embodiment, the anterior-posterior and medial-lateral dimensions of the target area of the joint model 36 of the patient's femur 18 and tibia 20 are increased by mathematical formulas. The resulting mathematically modified front-rear and inner-outer dimensions are then compared to the front-rear and inner-outer dimensions of the model of candidate jig blanks 50A, 50B. In one embodiment, the selected jig blank 50A, 50B does not exceed the mathematically modified dimensions of the patient's bones 18, 20, and the mathematically modified anterior surface of the patient's bones 18, 20— A jig blank having front-rear and inner-outer dimensions that are closest in size to the rear and inner-outer dimensions. In one embodiment, the jig blank selection method selects a jig blank 50 that is as close as possible to the patient's knee shape, thereby minimizing the machining required to generate the jig 2 from the jig blank. Will do.

  As described with respect to FIGS. 1F-1I, in one embodiment, each arthroplasty cutting jig 2 includes an inner portion and an outer portion. The inner part has dimensions specific to the curved shape of the patient's bone, which is the focus of arthroplasty. Thus, when the arthroplasty is a TKR operation, the jig is a femur jig and / or a tibial jig. The femur jig will have an inner portion specifically shaped to match the damaged curved surface of the lower end of the patient's femur, ie, the end of the joint. The tibial jig will have a medial portion that is specifically shaped to match the damaged curved surface of the upper end of the patient's tibia, the joint end.

  In one embodiment, due to the jig blank grouping and selection method, the outer portion of each arthroplasty cutting jig 2 has a size that is substantially similar to the patient's femur and tibia 3D joint model 36. However, the outer part of the jig 2 may be mathematically modified to provide the appropriate structural integrity for the cutting jig 2, and the outer part of the jig 2 may exceed the 3D femur and tibial model in various directions, The resulting cutting jig 2 may have sufficient jig material between the outer and inner portions of the jig 2 to provide adequate structural strength.

  As can be seen from block 140 of FIG. 1D, when the system 4 selects a femur and tibial jig blank 50 having a size and shape that is substantially similar to the size and shape of the patient's femur and tibial computer joint model 36, The system 4 applies a 3D computer surface model 40 of the shape 42 of interest to the femur 18 and tibia 20 to a selected femur and tibia jig 38, or a jig blank 50 that is more suitable in one embodiment of the present invention. Are superimposed on the inner part of the corresponding 3D computer model. As can be seen from block 145 of FIG. 1E, the result is a computer model of the femur and tibia jig 2 in the form of “jig data” 46, which is (1) the femur and tibia of the patient. A corresponding outer portion that closely approximates the overall size and shape, and (2) a corresponding inner portion having a curved surface that matches the shape 42 of interest of the patient's femur 18 and tibia 20.

  The system 4 causes the CNC machine 10 to produce the actual jig 2 from the actual jig material using the data of the jig computer model (ie, “jig data” 46). The results are as follows: (1) the patient's actual femur and tibia, the outer part roughly matching in size and overall shape, and (2) the actual dimensions and shape of the shape 42 of interest of the patient's femur and tibia. Automatic production of actual femur and tibia jig 2 having a medial part with dimensions and shape specific to the corresponding patient. The system 4 and method disclosed herein allows for the efficient manufacture of an arthroplasty jig 2 that is specialized in patient-specific bone shapes.

  The jig 2 and system 4 and method for manufacturing such a jig are illustrated here for knee and TKR surgery. However, those skilled in the art will appreciate that the jig 2 and system 4 and method of manufacturing such a jig can be easily modified for use in other joints and joint replacements such as elbows, shoulders, hips, etc. Let's go. Accordingly, the disclosure contained herein relating to the jig 2 and system 4 and methods for manufacturing such jigs is not limited to knee and TKR surgery, and should be considered to encompass all types of joint surgery.

  c. Definition of the 3D surface model of the arthroplasty target area at the lower end of the femur for use as the curved surface of the medial part of the femoral arthroplasty cutting jig

  To describe a method for generating a 3D model 40 of the region of interest 42 of the damaged lower end 204 of the patient's femur 18, reference is made to FIGS. FIG. 2A is a damaged lower end of the patient's femur 18, ie, an anterior-posterior (“AP”) image slice 208 of the knee joint end 204, where the image slice 208 is in the target area 42 of the damaged lower end 204. A corresponding open loop contour segment 210 is included. FIG. 2B shows a plurality of image slices (16-1, 16-2,... 16-n) with corresponding open loop contour segments (210-1, 210-2,... 210-n) The contour line segments 210 are accumulated to generate the 3D model 40 of the target area 42. FIG. 2C is a 3D model 40 of the region of interest 42 of the damaged lower end 204 generated using the open loop contour segments (210-1, 210-2,... 210-n) shown in FIG. 2B. 2D-2F are similar to FIGS. 2A-2C, respectively, but FIGS. 2D-2F relate to closed loop contours rather than open loop contours. FIG. 2G is a flowchart showing an outline of a method for manufacturing the femur jig 2A.

  As can be seen from FIGS. 1A, 1B and 2A, the imaging device 120 is used to generate a 2D image slice 16 of the damaged lower end of the patient's femur 18, the knee joint end 204. As shown in FIG. 2A, the 2D image 16 is an AP view of the femur 18. Depending on whether the imaging device 120 is an MRI imaging device or a CT imaging device, the image slice 16 is an MRI slice or a CT slice. The damaged lower end 204 includes a posterior condyle 212, an anterior femoral shaft curved surface 214, and a region of interest from the posterior condyle 212 to the anterior femoral shaft curved surface 214, that is, the target region 42. The target region 42 at the lower femur end may be the upper femoral end, ie, the articular contact surface of the lower femoral end that contacts the corresponding articulating surface of the distal knee joint.

  As shown in FIG. 2A, the image slice 16 shows the cancellous bone 216, the cortical bone 218 surrounding the cancellous bone, and the articular cartilage capsule of the cortical bone 218. The contour line 210 extends along the target region 42 and directly adjacent to the cortical bone and cartilage, and outlines the target region 42 of the lower femoral end 204. Contour line 210 starts along point of interest 42 from point A on the posterior condyle 212 and extends to point B on the anterior femoral shaft curved surface 214.

  In one embodiment, as shown in FIG. 2A, the contour line 210 extends along the region of interest 42 and does not follow the rest of the curved surface of the lower femoral end 204. As a result, contour 210 forms an open loop that can be used to form an open loop region, ie, 3D computer model 40, as described below with respect to FIGS. 2B and 2C. The 3D computer model closely matches the 3D curved surface of the target region 42 at the lower end of the femur, as described with respect to block 140 in FIG. 1D. Thus, in one embodiment, the contour line is an open loop, and the entire cortical bone curved surface of the lower femur lower end 204 is not drawn. In one embodiment, open loop processing is also used to form a 3D surface model 36 from the 2D image 16, which is a rough replacement for the joint model 36 described in blocks 125-140 of FIG. 1D. It is used to generate the surface model 40 used to generate the “jig data” 46 described in blocks 145 to 150 in FIG. 1E.

  In one embodiment, as opposed to the open loop contour 210 shown in FIGS. 2A and 2B, the contour is a closed loop contour 210 ′, and as shown in FIG. 2D, the entire cortical bone surface at the lower end of the femur is shown. A contour is drawn to form a closed loop region. The closed loop contours 210'-1, ... 210'-n of each image slice 16-1, ... 16-n are combined as shown in Fig. 2E. The closed loop region requires analysis of the entire curved portion of the lower femur end 204 and forms a 3D model of the entire lower femur end 204 as shown in FIG. 2F. As described above, the 3D surface model obtained from the closed-loop process has many, if not all, parts in common with the curved surface of the 3D joint model 36. In one embodiment, the closed loop process can obtain a 3D volume anatomical joint solid model from the 2D image 16 by applying a mathematical algorithm. US Pat. No. 5,682,886, filed Dec. 26, 1995, which is hereby incorporated by reference in its entirety, applies a snake algorithm that forms a continuous boundary, or closed loop. After the femur contour is drawn, a 3D surface model is generated using a modeling process using, for example, the Bezier patch method. Other 3D modeling processes, such as commercially available 3D construction software as listed elsewhere in this specification, can be applied to generate 3D surface models for closed loop, volume solid modeling.

  In one embodiment, closed loop processing is used to form a 3D volume solid model 36 from the 2D image 16, and the volume model is essentially the same as the joint model 36 described in blocks 125-140 of FIG. 1D. is there. The 3D volume solid model 36 is used to generate the surface model 40 used to generate the “jig data” 46 described in blocks 145 to 150 in FIG. 1E.

  The formation of a 3D volume solid model of the entire lower femur end is more memory and time intensive than using an open loop contour to generate a 3D model of the region of interest 42 at the lower femur end. Thus, although the closed loop method is used in the systems and methods disclosed herein, the open loop method is preferred over the closed loop method for at least some embodiments.

  An example of the closed loop method is disclosed in Park's US patent application Ser. No. 11 / 641,569, filed January 17, 2007, entitled Improved Total Joint Arthroplasty System. This application is hereby incorporated by reference in its entirety.

  As can be seen from FIGS. 2B and 2G, the imaging device 120 generates a plurality of image slices (16-1, 16-2,... 16-n) through an iterative imaging operation (block 1000). Each image slice 16 has an open loop contour (210-1, 210-2,... 210-n) extending along the target region 42 as described with respect to FIG. 2A (block 1005). In one embodiment, each image slice is a 2 millimeter 2D image slice 16. System 4 collects multiple image slices (16-1, 16-2,... 16-n), and more specifically, multiple open loop contours (210-1, 210-2,... 210-n). The 3D femur surface computer model 40 shown in FIG. 2C is created (block 1010). This process for generating the surface model 40 is also described in the overview section with respect to blocks 100-105 in FIG. 1B and blocks 130-140 in FIG. 1D. Similar processing may be used for the closed loop contours shown in FIGS.

  As can be seen from FIG. 2C, the 3D femur surface computer model 40 is a 3D computer representation of the target region 42 at the lower end of the femur. In one embodiment, the 3D representation of the target site 42 is a 3D representation of the articular tibia contact surface at the distal end of the femur. Since the open loop generation 3D model 40 is a surface model of the corresponding tibial contact portion at the lower end of the femur, the open loop generation is opposite to the 3D model of the entire curved surface of the lower end of the femur, which is the result of the closed loop contour. The 3D model 40 is less time and memory intensive to generate.

  In one embodiment, the open loop generation 3D model 40 is a surface model of the end face facing the tibia at the lower end of the femur, as opposed to the 3D model of the entire lower end of the femur. The 3D model 40 can be used to identify a region of interest, i.e., a target site 42, where the target site is the corresponding tibial contact at the lower end of the femur, as previously described. Again, the open loop generation 3D model 40 is less time and memory intensive to generate than the 3D model of the entire distal femur curved surface generated by the closed loop contour. Accordingly, in at least some embodiments disclosed herein, the open loop contour method is preferred over the closed loop contour method. However, the system 4 and the method disclosed in the present application may use the open loop method or the closed loop method, and it is not desirable to limit to one of them.

  The 3D model 40 is the surface model of the target region 42 (ie, the 3D surface model generated by the open loop process and functions as the joint model 36), or the entire end surface facing the tibia at the lower femoral end (ie, Regardless of whether it is a 3D volume solid model generated by a closed loop process and functioning as a joint model 36, the data about the contour 210 is a surface rendering technique disclosed in any of the aforementioned US patent applications. Can be converted into a 3D contour computer model 40. For example, the surface rendering techniques used include point-to-point mapping techniques, surface normal vector mapping techniques, local surface mapping techniques, and global surface mapping techniques. Depending on the situation, one or a combination of each mapping technique can be used.

  In one embodiment, the 3D model 40 shown in FIG. 2C is generated by measuring the position coordinate values of each of the curved surface points at a series of intervals in the open loop region of FIG. 2B using the image slice 16. You may go. The mathematical model may then be used to estimate, ie calculate, the 3D model 40 of FIG. 2C. Examples of other medical imaging computer programs that can be used include, but are not limited to, Analyze from AnalyzeDirect from Overland, KS, and open software such as Paraview from Kitware Inc., and can be obtained at www.itk.org Includes Insight Toolkit ("ITK"), 3D Slicer available at www.slicer.org, and Mimics from Materialise, Ann Arbor, MI.

  An alternative or addition to the above-described system for generating the 3D model 40 shown in FIG. 2C, other systems for generating the 3D model 40 of FIG. 2C are non-uniform rational B-spline (“NURB”) programs or Bezier programs. Including surface rendering techniques. Each of these programs may be used to generate the 3D contour model 40 from the plurality of contour lines 210.

  In one embodiment, the NURB surface modeling technique is applied to a plurality of image slices 16, more specifically, a plurality of open loop contours 210 in FIG. 2B. The NURB software generates the 3D model 40 shown in FIG. 2C, and the 3D model 40 has a region of interest that includes both meshes and control points, that is, a target region 42. For example, see Ervin et al. Landscape Modeling, McGraw-Hill, 2001. This document is referred to in its entirety in this specification.

ここで，P(i,j)はnrows=(k1+1)及びncols=(k2+1)の頂点行列，W(i,j)は頂点ごとの頂点重みの行列，bi(s)は次数M1の多項式の行方向基底，すなわち混合，bj(t)は次数M2の多項式の列方向基底，すなわち混合，sは行方向の結び目のパラメータ配列，tは列方向の結び目のパラメータ配列を表わす。 In one embodiment, the NURB surface model technique uses the following surface formula:

Where P (i, j) is the vertex matrix with nrows = (k1 + 1) and ncols = (k2 + 1), W (i, j) is the vertex weight matrix for each vertex, and bi (s) is the degree The row direction basis of the polynomial of M1, ie, mixture, bj (t) is the column direction basis of the polynomial of degree M2, ie, mixture, s is the parameter array of knots in the row direction, and t is the parameter array of knots in the column direction.

In one embodiment, the Bezier surface modeling technique uses the Bezier formula (1972, Pierre Bezier) to generate a 3D model 40 as shown in FIG. A Bezier surface of order (n, m) is defined by a set of (n + 1) (m + 1) control points k _{i, j} . A Bezier surface associates a unit square with a smooth, continuous surface built in a space of the same dimension as (k _{i, j} ). For example, if all k are points in a four-dimensional space, the curved surface is in the four-dimensional space. This relationship also holds for 1-dimensional, 2-dimensional, 50-dimensional, etc. spaces.

で与えられ，ここで

はBernstein多項式であり，

は二項係数である。詳細については，Gruneほか，On Numerical Algorithm and Interactive Visualization for Optimal Control Problems, Journal of Computation and Visualization in Science, Vol. 1, No. 4, 1999年7月を参照されたい。同文献は本明細書において全体を参照する。 A two-dimensional Bezier surface can also be defined as a parametric surface, and the position of the point p as a function of the parametric coordinates u, v is relative to the unit square.

Where

Is a Bernstein polynomial,

Is a binomial coefficient. For details, see Grune et al., On Numerical Algorithm and Interactive Visualization for Optimal Control Problems, Journal of Computation and Visualization in Science, Vol. 1, No. 4, July 1999. This document is referred to in its entirety in this specification.

Various other surface rendering techniques are disclosed in other references. See, for example, the surface rendering techniques disclosed in the following publications:
Lorensen et al., Marching Cubes: A high Resolution 3d Surface Construction Algorithm, Computer Graphics, Vol. 21-3, pp. 163-169, 1987
Farin et al., NURB Curves & Surfaces: From Projective Geometry to Practical Use, Wellesley, 1995
Kumar et al., Robust Incremental Polygon Triangulation for Surface Rendering, WSCG, 2000
Fleischer et al., Accurate Polygon Scan Conversion Using Half-Open Intervals, Graphics Gems III, pp. 362-365, Code: pp. 599-605, 1992
Foley et al., Computer Graphics: Principles and Practice, Addison Wesley, 1990
Glassner, Principles of Digital Image Synthesis, Morgan Kaufmann, 1995. All these references are hereby incorporated by reference in their entirety.

  d. Selecting a jig material having a size and / or shape that most closely resembles the size of the patient's lower femoral end

  As described above, the arthroplasty jig 2, such as the femur jig 2A, includes an inner portion 100 and an outer portion 102. The femur jig 2A is formed from a femur jig material 50A, and the jig material is selected from a finite number of femur jig material sizes in one embodiment. Selection of the femur jig blank 50A compares the size and / or shape of the patient's lower femur end 204 with the size and / or shape of the various sizes of the femur jig blank 50A. This is done by selecting the femur jig blank 50A most closely similar to 204. The femur jig material 50A selected in this way has an outer side, that is, an outer side surface, that is, a curved surface 232, which forms the outer portion 102 of the femur jig 2A. The 3D surface computer model 40 described in the immediately preceding chapter of this specification is used to define the 3D curved surface 40 inside the computer model 230 of the femur jig blank 50A.

  Selecting a femoral jig blank 50A having an outer portion 232 that is close in size to the patient's lower femoral end 204 increases the likelihood of an exact alignment between the inner portion 230 and the patient's femur. Also, the amount of material that needs to be processed or otherwise removed from the jig blank 50A is reduced, thereby reducing material waste and manufacturing time.

  To illustrate how to select the jig blank 50 that most closely corresponds to the size and / or shape of the patient's lower femoral end, reference is first made to FIGS. FIG. 3A is a top perspective view of a left femur cutting jig blank 50AL having a predetermined dimension. FIG. 3B is a bottom perspective view of the jig blank 50AL shown in FIG. 3A. FIG. 3C is a plan view of the outside of the jig blank 50AL shown in FIG. FIG. 4A shows a plurality of available sizes of left femur jig blank 50AL, each drawn from the same viewpoint as FIG. 3C. FIG. 4B shows a plurality of available sizes of right femur jig blank 50AR, each drawn from the same perspective as FIG. 3C.

  A common jig material 50, such as a left jig material 50AL for generating a left femoral jig that can be used on the patient's left femur shown in FIGS. 3A-3C, includes a rear edge 240 and an anterior edge. 242, outer edge 244, inner edge 246, lateral condyle 248, medial condyle 250, lateral 232, and medial 230. The jig blank 50AL of FIGS. 3A-3C may be any one of several left femur jig blanks 50AL available in a limited number of standard sizes. For example, the jig material 50AL in FIGS. 3A to 3C is the i-th left femur jig material (where i = 1, 2, 3, 4,... M, m is the maximum number of left femur jig material sizes). Good.

  As shown in FIG. 3C, the front-rear length JAi of the jig blank 50AL is measured from the front edge 242 to the rear edge 240 of the jig blank 50AL. The inside-outside length JMi of the jig blank 50AL is measured from the outer edge 244 to the inner edge 246 of the jig blank 50AL.

As can be seen from FIG. 4A, a limited number of left femur jig blank sizes can be selected as the left femur jig blank size machined into the left femur cutting jig 2A. For example, in one embodiment, a left femur jig blank 50AL of 9 sizes (m = 9) can be used. As can be seen from FIG. 3C, each femur jig blank 50AL has an anterior-posterior / medial-lateral aspect ratio (eg, “JAi / JMi” aspect ratio) defined as JAi vs. JMi. As can be seen from FIG. 4A, the jig material 50AL-1 has an aspect ratio defined by "JA ₁ / JM ₁ ", and the jig material 50AL-2 has an aspect ratio defined by "JA ₂ / JM ₂ ". , Jig material 50AL-3 is the aspect ratio defined by "JA ₃ / JM ₃ ", jig material 50AL-4 is the aspect ratio defined by "JA ₄ / JM ₄ ", jig material 50AL-5 is "JA ₅ " Aspect ratio defined by "/ JM ₅ ", jig material 50AL-6 defined by "JA ₆ / JM ₆ ", jig material 50AL-7 defined by "JA ₇ / JM ₇ " The jig material 50AL-8 has an aspect ratio defined by “JA ₈ / JM ₈ ”, and the jig material 50AL-9 has an aspect ratio defined by “JA ₉ / JM ₉ ”.

  The jig blank aspect ratio is used to design the left femur jig 2A having a size specific to the shape of the patient's left femur. In one embodiment, the jig blank aspect ratio may be the outer dimension of the left femur jig 2A. In another embodiment, the jig blank aspect ratio may be applied to a left femur jig manufacturing procedure for selecting a left jig blank 50AL having parameters close to the desired dimensions of the left femur jig 2A. This embodiment can reduce the amount of machining required to produce the desired jig 2 from the selected jig blank 50, thus improving the cost efficiency of the left femur jig manufacturing process.

In FIG. 4A, the direction N-1 indicates that the jig aspect ratio increases from the jig 50AL-3 to the jig 50AL-2 and the jig 50AL-1. Here, "JA ₃ / JM ₃ "<"JA ₂ / JM ₂ "<"JA ₁ / JM ₁ ". An increase in the ratio of each jig 50AL indicates that the JMi value of each jig is constant and the corresponding JAi value increases. In other words, JA ₃ <JA ₂ <JA ₁ and JM ₃ = JM ₂ = JM ₁ , so "JA ₃ / JM ₃ "<"JA ₂ / JM ₂ "<"JA ₁ / JM ₁ " . An example of an increase level is an increase of 5% to 20%.

The same ground applies for directions N-2 and N-3. For example, the direction N-2 indicates that the jig aspect ratio increases from the jig 50AL-6 to the jig 50AL-5 and the jig 50AL-4. Here, “JA ₆ / JM ₆ ” <“JA ₅ / JM ₅ ” <“JA ₄ / JM ₄ ”. An increase in the ratio of each jig 50AL indicates that the JMi value of each jig is constant and the corresponding JAi value increases. The direction N-3 indicates that the jig aspect ratio increases from the jig 50AL-9 to the jig 50AL-8 and jig 50AL-7. Here, “JA ₉ / JM ₉ ” <“JA ₈ / JM ₈ ” <“JA ₇ / JM ₇ ”. An increase in the ratio of each jig 50AL indicates that the JMi value of each jig is constant and the corresponding JAi value increases.

  As can be seen from the scatter diagram 300 shown in FIG. 7 and the description of the latter part of this specification, the direction E-1 corresponds to the diagonal line connecting the group 1, the group 4, and the group 7. Similarly, the direction E-2 corresponds to the diagonal line connecting the group 2, the group 5, and the group 8. The direction E-3 corresponds to the diagonal line connecting the group 3, the group 6, and the group 9.

As shown in FIG. 4A, the jig aspect ratio is constant between the jigs 50AL-2, 50AL-5, and 50AL-8 along the direction E-2, and “JA ₂ / JM ₂ ” = “JA ₅ / JM ₅ "=" JA ₈ / JM ₈ ". However, the dimensions of 50AL-5 are larger and longer than jig 50AL-2 compared to jig 50AL-2. This is because the JA ₅ value of the jig 50AL-5 increases to some extent in all directions of the X, Y, and Z axes in proportion to the increase in the JM ₅ value. Similarly, since the JA ₈ value increases to some extent in all directions of the X, Y and Z axes in proportion to the increase in the JM ₈ value, the dimension of 50AL-8 is larger and longer than the jig 50AL-5. . An example of an increase is an increase from 5% to 20%.

The same rationale applies to directions E-1 and E-3. For example, in the direction E-3, the jig aspect ratio is constant among the jigs 50AL-3, 50AL-6, and 50AL-9. Because both the JA ₆ and JM ₆ values of jig 50AL-6 increase proportionally in all directions of the X, Y and Z axes, the dimensions of 50AL-6 are larger and longer than jig 50AL-3. . Since both the JA ₉ and JM ₉ values of the jig 50AL-9 increase proportionally in all directions of the X, Y, and Z axes, the dimensions of the 50AL-9 are larger and longer than the jig 50AL-6. .

As can be seen from FIG. 4B, a limited number of right femur jig blank sizes can be selected as the right femur jig blank size to be machined into the right femur cutting jig 2A. For example, in one embodiment, nine sizes (m = 9) of the right femur jig material 50AR can be used. As can be seen from FIG. 3C, each femur jig blank 50AR has an anterior-posterior / medial-lateral aspect ratio (eg, “JAi / JMi” aspect ratio) defined as JAi vs. JMi. As can be seen from FIG. 4B, the jig material 50AR-1 has an aspect ratio defined by "JA ₁ / JM ₁ ", and the jig material 50AR-2 has an aspect ratio defined by "JA ₂ / JM ₂ ". , Jig material 50AR-3 is the aspect ratio defined by "JA ₃ / JM ₃ ", jig material 50AR-4 is the aspect ratio defined by "JA ₄ / JM ₄ ", jig material 50AR-5 is "JA ₅ " Aspect ratio defined by "/ JM ₅ ", jig material 50AR-6 is defined by "JA ₆ / JM ₆ ", and jig material 50AR-7 is defined by "JA ₇ / JM ₇ " The jig material 50AR-8 has an aspect ratio defined by “JA ₈ / JM ₈ ”, and the jig material 50AR-9 has an aspect ratio defined by “JA ₉ / JM ₉ ”.

  The jig blank aspect ratio is used to design the right femur jig 2A having a size specific to the shape of the patient's right femur. In one embodiment, the jig blank aspect ratio may be the outer dimension of the right femur jig 2A. In another embodiment, the jig blank aspect ratio may be applied to a right femur jig manufacturing procedure for selecting a right jig blank 50AR having parameters close to the desired dimensions of the right femur jig 2A. This embodiment can reduce the amount of machining required to produce the desired jig 2 from the selected jig blank 50, thereby improving the cost efficiency of the right femur jig manufacturing process.

In FIG. 4B, the direction N-1 indicates that the jig aspect ratio increases from the jig 50AR-3 to the jig 50AR-2 and the jig 50AR-1. Here, "JA ₃ / JM ₃ "<"JA ₂ / JM ₂ "<"JA ₁ / JM ₁ ". An increase in the ratio of each jig 50AR indicates that the JMi value of each jig is constant and the corresponding JAi value increases. In other words, JA ₃ <JA ₂ <JA ₁ and JM ₃ = JM ₂ = JM ₁ , so "JA ₃ / JM ₃ "<"JA ₂ / JM ₂ "<"JA ₁ / JM ₁ " . An example of an increase level is an increase of 5% to 20%.

The same ground applies for directions N-2 and N-3. For example, the direction N-2 indicates that the jig aspect ratio increases from the jig 50AR-6 to the jig 50AR-5 and the jig 50AR-4. Here, “JA ₆ / JM ₆ ” <“JA ₅ / JM ₅ ” <“JA ₄ / JM ₄ ”. An increase in the ratio of each jig 50AR indicates that the JMi value of each jig is constant and the corresponding JAi value increases. The direction N-3 indicates that the jig aspect ratio increases from the jig 50AR-9 to the jig 50AR-8 and jig 50AR-7. Here, “JA ₉ / JM ₉ ” <“JA ₈ / JM ₈ ” <“JA ₇ / JM ₇ ”. An increase in the ratio of each jig 50AR indicates that the JMi value of each jig is constant and the corresponding JAi value increases.

As shown in FIG. 4B, the jig aspect ratio is constant between the jigs 50AR-2, 50AR-5 and 50AR-8 along the direction E-2, and "JA ₂ / JM ₂ " = "JA ₅ / JM ₅ "=" JA ₈ / JM ₈ ". However, the dimensions of 50AR-5 are larger and longer than jig 50AR-2 compared to jig 50AR-2. This is because the JA ₅ value of the jig 50AR-5 increases to some extent in all directions of the X, Y, and Z axes in proportion to the increase in the JM ₅ value. Similarly, since the JA ₈ value increases to some extent in all directions of the X, Y and Z axes in proportion to the increase in the JM ₈ value, the size of 50AR-8 is larger and longer than the jig 50AR-5. . An example of an increase is an increase from 5% to 20%.

The same rationale applies to directions E-1 and E-3. For example, in the direction E-3, the jig aspect ratio is constant among the jigs 50AR-3, 50AR-6, and 50AR-9. Both the JA ₆ and JM ₆ values of the jig 50AR-6 increase proportionally in all directions of the X, Y, and Z axes, so the dimensions of the 50AR-6 are larger and longer than the jig 50AR-3. . Because both the JA ₉ and JM ₉ values of jig 50AR-9 increase proportionally in all directions of the X, Y, and Z axes, the size of 50AR-9 is larger and longer than jig 50AR-6. .

  The dimensions of the lower end of the patient's femur 18, i.e., the knee joint end 204, can be determined by analyzing the 3D surface model 40, i.e., the 3D joint model 36, in a manner similar to that described for the jig blank 50. For example, as shown in FIG. 5, a 3D surface model 40 of the patient's left femur 18 viewed from the distal to proximal direction, ie, an axial view of the 3D joint model 36, as shown in FIG. The lower end 204 of the model 40, the joint model 36, includes an anterior edge 260, a posterior edge 262, an inner edge 264, an outer edge 266, a medial condyle 268, and a lateral condyle 270. The femur dimensions are measured with respect to the lower end surface of the patient's femur 18, ie, the tibial joint sliding surface 204, by analyzing the 3D surface model 40 of the 3D joint model 36. These femur dimensions are then used to set the femur jig dimensions and select the appropriate femur jig.

  As shown in FIG. 5, the lower end 204 of the patient's femur 18 (ie, the lower end of the surface model 40 of the joint model 36, whether formed by an open loop analysis or a closed loop analysis). 204), the anterior-posterior length fAP is a length measured from the anterior margin 262 of the lateral femoral groove to the posterior margin 260 of the lateral femoral condyle 270. The medial-lateral length fML of the lower end 204 of the patient's femur 18 is the length measured from the inner edge 264 of the medial condyle 268 to the outer edge 266 of the lateral condyle 270.

  In one embodiment, the anterior-posterior length fAP and medial-lateral length fML of the lower femoral end 204 can be used for the aspect ratio fAP / fML of the lower femoral end. By collecting and statistically analyzing the knee aspect ratio fAP / fML of a large number of patients (eg, hundreds, thousands, tens of thousands, etc.), the most universal of jig materials that accommodate a large number of patient knees A good aspect ratio can be determined. This information can then be used to determine which one, two, three, etc. aspect ratio is likely to accommodate the maximum number of patient knees.

  The system 4 includes the patient's femur 18 obtained by the surface model 40 of the joint model 36 (whether the joint model 36 is a 3D model generated by an open loop process or a 3D volume solid model generated by a closed loop process). Is analyzed to obtain data on the anterior-posterior length fAP and medial-lateral length fML of the femoral lower end 204. As can be seen from FIG. 6 showing the selected model jig blank 50AL of FIG. 3C superimposed on the model femur lower end 204 of FIG. 5, the femur dimension length fAP, fML is the jig blank dimension length jAP, Compared with jML, it determines which jig material model to select as the starting point of processing and the outer surface model of the jig model.

  As shown in FIG. 6, the planned left femur jig blank 50AL is superimposed so as to mate with the lower left femur end 204 of the patient's anatomy model represented by the surface model 40 or joint model 36. The jig blank 50AL covers most of the medial condyle 268 and lateral condyle 270, and the small condylar region including t1, t2, and t3 remains exposed. The medial medial condyle site t1 represents a site between the inner edge 264 of the medial condyle 268 and the inner edge 246 of the jig blank 50AL. The outer medial-lateral condylar site t2 represents a site between the outer edge 266 of the outer condyle 270 and the outer edge 244 of the jig blank 50AL. The posterior front-rear part t3 represents a condylar part between the rear edge 260 of the outer condyle 270 and the rear edge 240 of the jig blank 50AL.

The anterior edge 242 of the jig blank 50AL extends beyond the anterior edge 262 of the left lower femoral lower end 204 indicated by an anterior-posterior overhang t4. In particular, the front anterior-rear overhang t4 represents a portion between the front edge 262 of the outer groove of the lower femur lower end 204 and the front edge 242 of the jig blank 50AL. By acquiring and using anterior femoral-posterior fAP data and femoral medial-lateral fML data, the system 4 can change the size of the femur jig blank 50AL according to the following formula:
jFML = fML-t1-t2, jFAP = fAP-t3 + t4
Here, jFML is the medial-lateral length of the femur jig blank 50AL, and jFAP is the anterior-posterior length of the femur jig blank 50AL. In one embodiment, t1, t2, t3, and t4 are in the following ranges.
2mm ≤ t1 ≤ 6mm, 2mm ≤ t2 ≤ 6mm, 2mm ≤ t3 ≤ 12mm, 15mm ≤ t4 ≤ 25mm
In another embodiment, t1, t2, t3, and t4 are the following values:
t1 = 3mm, t2 = 3mm, t3 = 6mm, t4 = 20mm

  FIG. 7A is an exemplary scatter plot 300 for selecting a jig material size suitable for the lower end 204 of the patient's femur 18 from a plurality of candidate jig material sizes. In one embodiment, the X axis represents the patient's femoral medial-lateral length fML in millimeters and the Y axis represents the patient's anterior-posterior femoral length fAP in millimeters. In one embodiment, the scatter plot is divided into several jig material size groups, each group containing one region of the scatter chart 300 and associated with specific parameters JMr, JAr for specific candidate jig material sizes. .

  In one embodiment, the example scatter plot 300 shown in FIG. 7A includes nine material size groups, each group belonging to one candidate jig material size. However, depending on the embodiment, the scatter plot 300 may include more jig material size groups or fewer jig material size groups. The greater the number of jig material size groups, the greater the number of candidate jig material sizes, and the selected candidate jig material size will be more specific to the patient's knee shape and the resulting jig 2. As the selected candidate jig blank size is more dimensionally specified, the amount of machining required to manufacture the desired jig 2 from the selected candidate jig blank 50 is reduced.

  Conversely, the smaller the number of jig material size groups, the smaller the number of candidate jig material sizes, and the selected candidate jig material size will not be dimension specific due to the patient's knee shape and the resulting jig 2. The more the selected candidate jig blank size is more dimensionally specified, the more machining is required to produce the desired jig 2 from the selected candidate jig blank 50, and extra roughing in the jig manufacturing procedure. Will increase.

As can be seen from FIG. 7A, in one embodiment, the nine jig material size groups in the scatter diagram 300 have the following parameters JMr and JAr. Group 1 has parameters JM ₁ and JA ₁ . JM ₁ represents the medial-lateral length of the first femur jig blank size, and JM ₁ = 70 mm. JA ₁ represents the anterior-posterior length of the first femur jig blank size, JA ₁ = 70.5 mm. Group 1 includes patient femur fML and fAP data in the range of 55 mm <fML <70 mm and 61 mm <fAP <70.5 mm.

Group 2 has parameters JM ₂ and JA ₂ . JM ₂ represents the medial-lateral length of the second femur jig blank size, and JM ₂ = 70 mm. JA ₂ represents the anterior-posterior length of the second femur jig blank size, JA ₂ = 61.5 mm. Group 2 includes femur fML and fAP data for patients with a range of 55 mm <fML <70 mm and 52 mm <fAP <61.5 mm.

Group 3 has parameters JM ₃ and JA ₃ . JM ₃ represents the medial-lateral length of the 3rd femur jig blank size, JM ₃ = 70mm. JA ₃ represents the anterior-posterior length of the third femur jig blank size, JA ₃ = 52 mm. Group 3 includes femur fML and fAP data for patients with a range of 55 mm <fML <70 mm and 40 mm <fAP <52 mm.

Group 4 has parameters JM ₄ and JA ₄ . JM ₄ represents the medial-lateral length of the 4th femur jig blank size, JM ₄ = 85mm. JA ₄ represents the anterior-posterior length of the 4th femur jig blank size, JA ₄ = 72.5 mm. Group 4 includes patient femur fML and fAP data in the range of 70 mm <fML <85 mm and 63.5 mm <fAP <72.5 mm.

Group 5 has parameters JM ₅ and JA ₅ . JM ₅ represents the medial-lateral length of the fifth femur jig blank size, JM ₅ = 85 mm. JA ₅ represents the anterior-posterior length of the fifth femur jig blank size, JA ₅ = 63.5 mm. Group 5 includes patient femur fML and fAP data in the range of 70 mm <fML <85 mm and 55 mm <fAP <63.5 mm.

Group 6 has parameters JM ₆ and JA ₆ . JM ₆ represents the medial-lateral length of the 6th femur jig blank size, JM ₆ = 85mm. JA ₆ represents the anterior-posterior length of the sixth femur jig blank size, JA ₆ = 55 mm. Group 6 includes femur fML and fAP data for patients in the range 70 mm <fML <85 mm and 40 mm <fAP <55 mm.

Group 7 has parameters JM ₇ and JA ₇ . JM ₇ represents the medial-lateral length of the 7th femur jig blank size, JM ₇ = 100 mm. JA ₇ represents the anterior-posterior length of the seventh femur jig blank size, JA ₇ = 75 mm. Group 7 includes femur fML and fAP data for patients in the range of 85 mm <fML <100 mm and 65 mm <fAP <75 mm.

Group 8 has parameters JM ₈ and JA ₈ . JM ₈ represents the medial-lateral length of the 8th femur jig blank size, JM ₈ = 100 mm. JA ₈ represents the anterior-posterior length of the eighth femur jig blank size, JA ₈ = 65 mm. Group 8 includes femur fML and fAP data for patients in the range of 85 mm <fML <100 mm and 57.5 mm <fAP <65 mm.

Group 9 has parameters JM ₉ and JA ₉ . JM ₉ represents the medial-lateral length of the 9th femur jig blank size, JM ₉ = 100mm. JA ₉ represents the anterior-posterior length of the ninth femur jig blank size, JA ₉ = 57.5 mm. Group 9 includes patient femur fML and fAP data in the range of 85 mm <fML <100 mm and 40 mm <fAP <57.5 mm.

  As can be seen from FIG. 7B, which is a flow chart illustrating an embodiment of a process for selecting an appropriately sized jig blank, the anterior-posterior length fAP and medial-lateral length fML of the bone are determined by the surface model 40 of the joint model 36. Is measured with respect to the lower end 204 (block 2000). The bone lengths fAP and fML of the lower end 204 are mathematically modified by the above-described jFML and jFAP formulas to become the minimum femoral jig blank anterior-posterior length jFAP and medial-lateral length jFML (block 2010). The mathematically modified bone lengths fAP, fML, or more specifically, the minimum femoral jig material anterior-posterior length jFAP and medial-lateral length jFML are the jig materials of scatter plot 300 of FIG. 7A. Reference is made to the dimensions (block 2020). The scatter diagram 300 can graphically represent the lengths of candidate femur jig materials that form the jig material library. The femur jig blank 50A is selected with a jig blank size that is still large enough to accommodate the minimum femur jig blank anterior-posterior length jFAP and medial-lateral length jFML (block 2030). .

  In one embodiment, the outside of the selected jig blank size is used as the outer surface model of the jig model, as will be described below. In one embodiment, the selected jig blank size is placed on a CNC machine and trimmed to a minimum femoral jig blank anterior-posterior length jFAP and medial-lateral length jFML, which is external to the femur jig 2A. Corresponds to actual jig material machined on the side or otherwise formed.

The method illustrated in FIG. 7B and related to the scatter plot 300 of FIG. 7A can be further understood by the following example. In FIG. 6 for the lower end 204 of the patient's femur 18, the measured patient's femur length is as follows: fML = 79.2mm and fAP = 54.5mm (Block 2000). As described above, the lower end 204 may be part of the surface model 40 of the joint model 36. Once the measured values of fML and fAP are measured from the lower end 204, the corresponding jig jFML data and jig jFAP data can be determined by the above-described jFML formula and jFAP formula as follows (block 2010).
jFML = fML-t1-t2, where t1 = 3mm, t2 = 3mm
jFAP = fAP-t3 + t4, where t3 = 6mm, t4 = 20mm
The calculation results by jFML formula and jFAP formula are jFML = 73.2mm and jFAP = 68.5mm.

As can be seen from the scatter plot 300 of FIG. 7A, the measured jig data (ie, jFML = 73.2 mm and jFAP = 68.5 mm) is included in group 4 of the scatter plot 300. Group 4 has predetermined femur jig material parameters (JM ₄ , JA ₄ ), ie JM ₄ = 85 mm and JA ₄ = 72.5 mm. This predetermined femur jig material parameter is the smallest of the various groups, but is still large enough for the minimum femoral material lengths jFAP and jFML. (Block 2020). This predetermined femur jig blank parameter (JM ₄ = 85 mm and JA ₄ = 72.5 mm) may be selected as an appropriate femur jig blank size (block 2030).

  In one embodiment, as shown in FIG. 3C, predetermined femur jig blank parameters (85 mm, 72.5 mm) may be applied to the femoral lateral jig dimensions. In other words, the jig blank outer portion is used as the jig model outer portion as will be described with reference to FIGS. Accordingly, the outer portion of the femur jig blank 50A does not need to be machined, and the uncorrected outer portion of the jig blank 50A having the predetermined jig blank parameters (85 mm, 72.5 mm) is used as the outer portion of the completed femur jig 2A. Can be used as

  In another embodiment, the femur jig blank parameters (85 mm, 72.5 mm) may be selected for jig manufacturing by machining. Therefore, the femur jig material 50A having the predetermined parameters (85mm, 72.5mm) is supplied to the machining process, and the outer portion of the femur jig material 50A is changed from the predetermined parameters (85mm, 72.5mm) to the desired femoral jig parameters ( 73.2mm, 68.5mm) to be the finished outer part of the femur jig 2A. By selecting a predetermined parameter (85 mm, 72.5 mm) relatively close to the desired femur jig parameter (73.2 mm, 68.5 mm), processing time and material waste are reduced.

  In order to reduce processing time and material waste, it is advantageous to use the jig material selection method described above, but in some embodiments the jig material is simply added to the bone lengths fAP, fML of all patients. Large enough to be applied is provided. Such a jig material is processed into desired jig material lengths jFAP and jFML and used as the outer surface of the completed jig 2A.

  In one embodiment, the number of candidate jig material size groups represented in the scatter diagram 300 is a function of the number of jig material sizes provided by the jig material manufacturer. For example, the first scatter diagram 300 relates only to jig materials manufactured by Company A that provides nine different jig material sizes. Therefore, the scatter diagram 300 has nine jig material size groups. The second scatter diagram 300 pertains only to jig materials produced by Company B that provides 12 different jig material sizes. Therefore, the scatter diagram 300 has 12 jig material size groups.

  As shown in the scatter diagram 300 of FIG. 7A, for example, the jig material library has a plurality of candidate jig material sizes. Each candidate jig material may have a unique combination of front-rear dimension size and inner-outer dimension size, but two or more candidate jig materials have a common aspect ratio jAP / jML, ie a shape. You may share. The candidate jig materials in the library are grouped along the diagonal lines of the scatter diagram 300 according to the aspect ratio jAP / jML.

  In one embodiment, the jig material aspect ratio jAP / jML may be used to select a jig material shape that can be processed and processed to fit a larger or smaller individual.

  As can be seen from FIG. 7A, as part of the femur jig design study, 98 osteoarthritis (OA) patients with knee injuries were entered into the scatter plot 300. The femur fAP and fML data of each patient was measured and corrected by the above-mentioned jFML and jFAP formulas to obtain patient jig material data (jFML, jFAP). The patient jig material data was then entered as points in the scatter plot 300. As can be seen from FIG. 7A, there are no patient points other than the available group parameters. Such a process can be used to set the group parameters and the number of groups required.

  In one embodiment, the selected jig blank parameter may be a femoral jig outer dimension specific to the patient's knee shape. In another embodiment, the selected jig blank parameters may be selected during the manufacturing process.

  e. Formation of 3D femur jig model

  To illustrate an example of a method for generating a 3D femur jig model 346 that roughly corresponds to the “integrated jig data” 48 described for block 150 of FIG. 1E, FIGS. 3A-3C, 8A-8B, 9A-9C, , 10A to 10B. 3A to 3C are various views of the femur jig blank 50A. 8A to 8B are an outer perspective view and an inner perspective view of the femur jig blank outer surface model 232M, respectively. 9A and 9B are external perspective views of the combined femur jig blank outer surface model 232M and bone surface model 40, and FIG. 9C is a cross-section of the combined model 232M, 40 along section line 9C-9C of FIG. 9B. FIG. FIGS. 10A and 10B each integrates “saw cutting and drilling data” 44 into the jig model 346, resulting in an integrated jig model, or complete jig model 348, that roughly corresponds to the “integrated jig data” 48 described with respect to block 150 of FIG. 1E. FIG. 6 is an outer and inner perspective view of the obtained femur jig model 346 after the first step.

  As can be seen from FIGS. 3A-3C, the jig blank 50 </ b> A having the selected predetermined dimensions described with respect to FIG. 7B includes an inner surface 230 and an outer surface 232. The outer surface model 232M shown in FIGS. 8A and 8B is extracted or otherwise generated from the outer surface 232 of the jig blank model 50A. Accordingly, the outer surface model 232M is based on the jig material aspect ratio of the selected femur jig material 50A as described with reference to FIG. 7B, and has dimensions specific to the patient's knee shape. The femur jig surface model 232M can be extracted or otherwise generated from the jig blank model 50A of FIGS. 3A-3C using any of the computer surface rendering techniques described above.

  As can be seen from FIGS. 9A-9C, the outer surface model 232M is combined with the femur surface model 40 to form the outer and inner surfaces of the femur jig model 346, respectively. The femur surface model 40 represents the inner surface of the femur jig 2 </ b> A, that is, the capture surface, and corresponds to the femoral arthroplasty target region 42. In this way, the model 40 allows the obtained femur jig 2A to be indexed to the arthroplasty target region 42 of the patient's femur 18 so that the obtained femur jig 2A is being subjected to the arthroplasty procedure. The arthroplasty target region 42 is captured. The two surface models 232M, 40 are combined into a patient-specific jig model 346 for manufacturing the femur jig 2A.

  As can be seen from FIGS. 9B and 9C, when the models 232M, 40 are properly aligned, a gap is created between the two models 232M, 40. The prepared models 232M and 40 are subjected to an image stitching method, that is, an image stitching tool, to combine the two surface models into one, and the 3D computer generated jig model 346 of FIG. 9B is combined with the integrated jig model 348 shown in FIGS. 10A and 10B. A jig model 346 shown in FIG. 9B is formed as a single unit having a similar appearance to each other, which is combined into one and filled-in. In one embodiment, the jig model 346 may generally correspond to the description of “jig data” 46 described with respect to block 145 of FIG. 1E.

As can be seen from FIGS. 9B and 9C, the geometric gap between the two models 232M, 40, some of which will be described below for thicknesses P ₁ , P ₂ and P ₃ , is a cutting instrument during TKA surgery. Due to the width and length of the slot that accepts and guides and the length of the drill bit, a certain space can be provided between the two models 232M, 40. The resulting femur jig model 348 shown in FIGS. 10A and 10B may be a 3D volume model generated from the 3D surface models 232M, 40, so that a space, ie, a gap, is provided between the 3D surface models 232M, 40. . The resulting 3D volume jig model 348 can be used to generate an actual physical 3D volume femur jig 2A.

In some embodiments, the image processing procedure may include a model modification procedure that modifies the jig model 346 after alignment of the two models 232M, 40. For example, without limitation, various methods of model modification include user-guided correction, crack identification and filling, and manifold connectivity generation as described in the following literature: Including.
Nooruddin et al., Simplification and Repair of Polygonal Models Using Volumetric Techniques, IEEE Trans. On Visualization and Computer Graphics, Vol. 9, No. 2, April-June 2003
Erikson, C., Error Correction of a Large Architectural Model: The Henderson County Courthouse, Technical Report TR95-013, Dept. of Computer Science, Univ. Of North Carolina at Chapel Hill, 1995
Khorramabdi, D., A Walk through the Planned CS Building, Technical Report UCB / CSD 91/652, Computer Science Dept., Univ. Of California at Berkeley, 1991
Morvan et al., IVECS: An Interactive Virtual Environment for the Correction of .STL files, Proc. Conf. Virtual Design, August 1996
Bohn et al., A Topology-Based Approach for Shell-Closure, Geometric Modeling for Product Realization, PR Wilson et al., Pp. 297-319, North-Holland, 1993
Barequet et al., Filling Gaps in the Boundary of a Polyhedron, Computer Aided Geometric Design, Vol. 12, No. 2, pp.207-229, 1995
Barequet et al., Repairing CAD Models, Proc. IEEE Visualization '97, pp. 363-370, October 1997
Gueziec et al., Converting Sets of Polygons to Manifold Surfaces by Cutting and Stitching, Proc. IEEE Visualization '98, pp. 383-390, October 1998, all of which are incorporated herein in their entirety.

As can be seen from FIGS. 10A and 10B, the integrated jig model 348 may include several features as desired by the surgeon. For example, the jig model 348 may include a slot 30 for receiving and guiding a bone saw and a drill hole 32 for receiving and guiding a bone drill bit. As can be seen from FIGS. 9B and 9C, the femoral jig 2A obtained is sufficient to properly support and guide the bone saw and drill bit without being distorted or deformed during the arthroplasty procedure. In order to have structural integrity, the gap 350 between the models 232M, 40 may have the following offsets P ₁ , P ₂ and P ₃ .

As can be seen in FIGS. 9B-10B, in one embodiment, the thickness P ₁ extends along the length of the front drill hole 32A between the models 232M, 40 and is received during the arthroplasty procedure. Support and guide. The thickness P ₁ may be at least about 4 mm or at least about 5 mm. The diameter of the front drill hole 32A may be configured to accept a cutting tool having a diameter of at least 1/3 inch.

The thickness P ₂ extends along the length of the saw slot 30 between the models 232M, 40, supports the bone saw accepted during the arthroplasty procedure induced. The thickness P ₂ may be at least about 10 mm or at least about 15 mm.

The thickness P ₃ extends along the length of the rear drill holes 32P between the models 232M, 40, supports a bone drill received during the arthroplasty procedure induced. The thickness P ₃ may be a thickness of at least about 5mm, or at least about 8 mm. The diameter of the drill hole 32 may be at least 0.85 mm (1/3 inch) and may be configured to accept a cutting instrument.

In addition to providing a sufficiently long surface to guide the received drill bit or saw, the various thicknesses P ₁ , P ₂ and P ₃ can be used to cut the femur during femoral jig 2A TKR surgery. , Structurally designed to withstand the powerful treatment of drilling and drilling.

As shown in FIGS. 10A and 10B, the integrated jig model 348 includes:
A shape 400 that matches the distal portion of the patient's medial condylar cartilage
A shape 402 that matches the distal portion of the patient's lateral condylar cartilage
Projection 404 that has a contact or heel shape and can securely engage the jig 2A obtained during the TKR operation with the anterior femoral joint surface of the patient.
A plane 406 that provides a blank label area listing information about the patient, surgeon and / or surgical procedure
Also, as described above, the integrated jig model 348 may include a sawing slot 30 and a drill hole 32. The inner part or inner side 100 (and resulting femur jig 2A) of the jig model 348 is a femoral surface model 40 that captures the arthroplasty area 42 of the patient's femur 18 during the arthroplasty procedure.

  As can be seen with reference to block 105 of FIG. 1B and FIGS. 2A-2F, in one embodiment, when the models 40, 22 are generated by accumulating the image scan data 16, the models 40, 22 have a point P. Reference to point P may be a single point, a series of points, etc. that refer to and direct models 40, 22 to models 22, 28 used in the POP as described with respect to FIG. 1C. Any change reflected in the models 22 and 28 for the point P due to the POP (eg, the point P becomes the point P ′) is reflected in the point P related to the models 40 and 22 (FIG. 1D). (See block 135). Thus, as can be seen from block 140 of FIG. 1D and FIGS. 9A-9C, when jig material outer surface model 232M is combined with surface model 40 (ie, a surface model made from joint model 22) to generate jig model 346. , The jig model 346 is referenced and oriented with respect to the point P ′ and is roughly equivalent to the “jig data” 46 described with respect to block 145 of FIG. 1E.

  Since the jig model 346 is appropriately referenced and oriented with respect to the point P ′, the “saw cutting and drilling data” 44 described with respect to block 125 of FIG. 1E is appropriately integrated into the jig model 346 to produce FIG. The integrated jig model 348 shown in FIG. The integrated jig model 348 includes a sawing slot 30, a drill hole 32, and a surface model 40. Accordingly, the integrated jig model 348 is roughly equivalent to the “integrated jig data” 48 described in block 150 of FIG. 1E.

  As can be seen from FIG. 11 which is a perspective view of the integrated jig model 348 mated with the “joint model” 22, the inner surface 40 of the jig model 348 captures the arthroplasty target region 42 of the lower femoral end 204, thereby The jig model 348 is indexed to mate with the region 42. By referencing and orienting various models to points P, P ′ throughout the procedure, the sawing slot 30 and drill hole 32 allow the resulting femoral jig 2A to restore the patient's joint to its pre-degenerative state. Properly oriented to be sawed and drilled.

  As shown in FIG. 11, the integrated jig model 348 includes a jig body 500, a protrusion 502 on one side of the jig body 500, and two protrusions 504 and 506 on the other side. Processes 504, 506 coincide with the medial and lateral condylar cartilage. The protrusions 502, 504, 506 extend integrally from two opposite ends of the jig body 500.

  As can be seen from blocks 155-165 of FIG. 1E, the integrated jig 348, or more specifically, integrated jig data 48, is sent to the CNC machine 10 to process the femur jig 2A from the selected jig blank 50A. it can. For example, the integrated jig data 48 may be used to create a production file that provides automatic jig manufacturing instructions to the high speed production machine 10 as described in the various Park patent applications referenced above. Then, the high speed production machine 10 manufactures the arthroplasty femur jig 2A specialized for the patient from the femur jig material 50A according to the instruction.

  The obtained femur jig 2 </ b> A may have the shape of the integrated jig model 348. Therefore, as can be seen from FIG. 11, the femoral jig 2A obtained may have a slot 30 and a drill hole 32 formed on the protrusions 502, 504, and 506, as desired by the surgeon. The drill hole 30 is an IR / ER (inside / outside) rotational axis misalignment that may occur between the femoral cutting jig 2A and the patient's damaged articular surface during the TKR procedure distal femoral cutting. Can be opened to prevent. The slot 30 is opened to accept a cutting instrument such as a reciprocating saw blade for transverse cutting during the cutting of the TKR's distal femur.

  f. Definition of the 3D surface model of the arthroplasty target region at the upper end of the tibia for use as the curved surface of the inner part of the tibial arthroplasty cutting jig

  To describe a method for generating a 3D model 40 of the region of interest 42 of the damaged upper end 604 of the patient's tibia 20, reference is made to FIGS. FIG. 12A is a damaged upper end of the patient's tibia 20, ie, an anterior-posterior (“AP”) image slice 608 of the knee joint end 604, which also includes the damaged upper end 604 in the region of interest 42. A corresponding open loop contour segment 610 is included. FIG. 12B is a plurality of image slices (16-1, 16-2,... 16-n) with corresponding open loop contour segments (610-1, 610-2,. The contour line segments 610 are accumulated to generate the 3D model 40 of the target area 42. FIG. 12C is a 3D model 40 of the region of interest 42 of the damaged upper end 604 generated using the open loop contour segments (610-1, 610-2,... 610-n) shown in FIG. 12B. .

  As can be seen from FIGS. 1A, 1B and 12A, the imaging device 120 is used to generate a 2D image slice 16 of the damaged upper end of the patient's tibia 20, ie, the knee joint end 604. As shown in FIG. 12A, the 2D image 16 is an AP view of the tibia 20. Depending on whether the imaging device 120 is an MRI imaging device or a CT imaging device, the image slice 16 is an MRI slice or a CT slice. The damaged upper end 604 includes a tibial plateau 612, an anterior tibial shaft curved surface 614, and a region of interest extending along the tibial meniscus from a portion of the lateral tibial plateau curved surface to the anterior tibial shaft curved surface 614, ie, a target region 42. The region of interest 42 at the upper tibia end may be the joint contact surface of the upper tibial end that contacts the lower femoral end, ie, the corresponding joint contact surface of the knee joint end.

  As shown in FIG. 12A, the image slice 16 shows the cancellous bone 616, the cortical bone 618 surrounding the cancellous bone, and the articular cartilage capsule of the cortical bone 618. The contour line 610 extends along the target region 42 and directly adjacent to the cortical bone and cartilage and outlines the target region 42 of the upper tibia distal end 604. Contour line 610 begins at point C on the lateral or medial tibia plateau 612 along the region of interest 42 (depending on whether the image slice extends through the lateral or medial portion of the tibia) It extends to a point D on the trunk curved surface 614.

  In one embodiment, as shown in FIG. 12A, the contour line 610 extends along the region of interest 42 and does not follow the rest of the curved surface of the upper tibial distal end 604. As a result, the contour line 610 forms an open loop, which can be used to form an open loop region, ie, the 3D computer model 40, as described below with respect to FIGS. 12B and 12C. The 3D computer model closely matches the 3D curved surface of the region of interest 42 at the upper end of the tibia, as described with respect to block 140 of FIG. 1D. Thus, in one embodiment, the contour is open loop and does not delineate the entire cortical bone surface of the upper tibia end 604. In one embodiment, open loop processing is also used to form a 3D surface model 36 from the 2D image 16, which is a rough replacement for the joint model 36 described in blocks 125-140 of FIG. 1D. It is used to generate the surface model 40 used to generate the “jig data” 46 described in blocks 145 to 150 in FIG. 1E.

  In one embodiment, the contour is a closed loop as described with respect to FIGS. 2D-2E, as opposed to the open loop contour 610 shown in FIGS. 12A and 12B, except for the flat loop contour belonging to the tibia instead of the femur. It is substantially the same as the outline 210 ′. Like the femur closed loop contour described with respect to FIG. 2D, the tibial closed loop contour outlines the entire cortical bone surface at the upper end of the tibia and forms a closed loop region. The tibial closed loop contour is combined in a manner similar to that described with respect to the femur contour shown in FIG. 2E. As a result, the tibial closed loop region requires analysis of the entire curved portion of the upper tibia end 604 and forms a 3D model of the entire upper tibia end 604 in a manner similar to the upper femur end 204 shown in FIG. 2F. . As described above, the 3D surface model obtained from the closed loop process has many, if not all, parts in common with the curved surface of the 3D tibial joint model 36. In one embodiment, the closed loop process can obtain a 3D volume anatomical joint solid model from the 2D image 16 by applying a mathematical algorithm. US Pat. No. 5,682,886, filed Dec. 26, 1995, which is hereby incorporated by reference in its entirety, applies a snake algorithm that forms a continuous boundary, or closed loop. After the outline of the tibia is drawn, a 3D surface model is generated using, for example, modeling processing by the Bezier patch method. Other 3D modeling processes, such as commercially available 3D construction software as listed elsewhere in this specification, can be applied to generate 3D surface models for closed loop, volume solid modeling.

  In one embodiment, closed loop processing is used to form a 3D volume solid model 36 from the 2D image 16, and the volume model is essentially the same as the joint model 36 described in blocks 125-140 of FIG. 1D. is there. The 3D volume solid model 36 is used to generate the surface model 40 used to generate the “jig data” 46 described in blocks 145 to 150 in FIG. 1E.

  The formation of a 3D volume solid model of the entire upper tibia end is more memory and time intensive than using an open loop contour to generate a 3D model of the region of interest 42 at the upper tibia end. Thus, although the closed loop method is used in the systems and methods disclosed herein, the open loop method is preferred over the closed loop method for at least some embodiments.

  An example of the closed loop method is disclosed in Park's US patent application Ser. No. 11 / 641,569, filed January 17, 2007, entitled Improved Total Joint Arthroplasty System. This application is hereby incorporated by reference in its entirety.

  As can be seen from FIGS. 12B and 2G, the imaging device 120 generates a plurality of image slices (16-1, 16-2,... 16-n) through an iterative imaging operation (block 1000). Each image slice 16 has an open loop contour (610-1, 610-2,... 610-n) extending along the target region 42 as described with respect to FIG. 12A (block 1005). In one embodiment, each image slice is a 2 millimeter 2D image slice 16. System 4 collects multiple image slices (16-1, 16-2,... 16-n), more specifically, multiple open loop contours (610-1, 610-2,... 610-n). The 3D femur surface computer model 40 shown in FIG. 12C is created (block 1010). This process for generating the surface model 40 is also described in the overview section with respect to blocks 100-105 in FIG. 1B and blocks 130-140 in FIG. 1D. A similar process may be used for the tibial closed loop contour.

  As can be seen from FIG. 12C, the 3D tibial surface computer model 40 is a 3D computer representation of the target region 42 at the upper end of the tibia. In one embodiment, the 3D representation of the target site 42 is a 3D representation of the articular femoral contact surface at the proximal end of the tibia. Since the open loop generation 3D model 40 is a surface model of the corresponding femoral contact portion of the upper tibia end, the open loop generation 3D is opposite to the 3D model of the entire curved surface of the upper tibia, which is the result of the closed loop contour. Model 40 is less time and memory intensive to generate.

  In one embodiment, the open loop generation 3D model 40 is a surface model of the end surface facing the femur at the upper end of the tibia, as opposed to the 3D model of the entire curved surface of the upper end of the tibia. The 3D model 40 can be used to identify a region of interest, i.e., a target site 42, where the target site is the corresponding femoral contact at the upper end of the tibia, as previously described. Again, the open loop generation 3D model 40 is less time and memory intensive to generate than the 3D model of the entire curved surface of the proximal tibia generated by the closed loop contour. Accordingly, in at least some embodiments disclosed herein, the open loop contour method is preferred over the closed loop contour method. However, the system 4 and the method disclosed in the present application may use the open loop method or the closed loop method, and it is not desirable to limit to one of them.

  The 3D model 40 is the surface model of the target region 42 (ie, the 3D surface model generated by the open loop process and functions as the joint model 22), or the entire distal surface facing the femur at the upper end of the tibia (ie, Regardless of whether it is a 3D volume solid model generated by closed-loop processing and functioning as a joint model 22, the data about the contour line 610 is the surface rendering technique disclosed in any of the aforementioned US patent applications. Can be converted into a 3D contour computer model 40. For example, the surface rendering techniques used include point-to-point mapping techniques, surface normal vector mapping techniques, local surface mapping techniques, and global surface mapping techniques. Depending on the situation, one or a combination of each mapping technique can be used.

  In one embodiment, the 3D model 40 shown in FIG. 12C is generated by measuring the position coordinate values of each of the curved surface points at a series of intervals of the open loop portion of FIG. 12B using the image slice 16. You may go. The 3D model 40 of FIG. 12C may be estimated, that is, calculated using a mathematical model. Examples of other medical imaging computer programs that can be used include, but are not limited to, Analyze from AnalyzeDirect from Overland, KS, and open software such as Paraview from Kitware Inc., and can be obtained at www.itk.org Includes Insight Toolkit ("ITK"), 3D Slicer available at www.slicer.org, and Mimics from Materialise, Ann Arbor, MI.

  An alternative to, or in addition to, the above-described system for generating the 3D model 40 shown in FIG. 12C is a non-uniform rational B-spline (“NURB”) program or Bezier program. Including surface rendering techniques. Each of these programs may be used to generate a 3D contour model 40 from a plurality of contour lines 610.

  In one embodiment, the NURB surface modeling technique is applied to a plurality of image slices 16, more specifically, a plurality of open loop contours 610 in FIG. 12B. The NURB software generates the 3D model 40 shown in FIG. 12C, and the 3D model 40 has a region of interest that includes both meshes and control points, that is, a target region 42. For example, see Ervin et al. Landscape Modeling, McGraw-Hill, 2001. This document is referred to in its entirety in this specification.

ここで，P(i,j)はnrows=(k1+1)及びncols=(k2+1)の頂点行列，W(i,j)は頂点ごとの頂点重みの行列，bi(s)は次数M1の多項式の行方向基底，すなわち混合，bj(t)は次数M2の多項式の列方向基底，すなわち混合，sは行方向の結び目のパラメータ配列，tは列方向の結び目のパラメータ配列を表わす。 In one embodiment, the NURB surface model technique uses the following surface formula:

Where P (i, j) is the vertex matrix with nrows = (k1 + 1) and ncols = (k2 + 1), W (i, j) is the vertex weight matrix for each vertex, and bi (s) is the degree The row direction basis of the polynomial of M1, ie, mixture, bj (t) is the column direction basis of the polynomial of degree M2, ie, mixture, s is the parameter array of knots in the row direction, and t is the parameter array of knots in the column direction.

In one embodiment, the Bezier surface modeling technique uses the Bezier formula (1972, Pierre Bezier) to generate a 3D model 40 as shown in FIG. 12C, where the model 40 has a region of interest, ie, a region of interest 42. A Bezier surface of order (n, m) is defined by a set of (n + 1) (m + 1) control points k _{i, j} . A Bezier surface associates a unit square with a smooth, continuous surface built in a space of the same dimension as (k _{i, j} ). For example, if all k are points in a four-dimensional space, the curved surface is in the four-dimensional space. This relationship also holds for 1-dimensional, 2-dimensional, 50-dimensional, etc. spaces.

で与えられ，ここで

はBernstein多項式であり，

は二項係数である。詳細については，Gruneほか，On Numerical Algorithm and Interactive Visualization for Optimal Control Problems, Journal of Computation and Visualization in Science, Vol. 1, No. 4, 1999年7月を参照されたい。同文献は本明細書において全体を参照する。 A two-dimensional Bezier surface can also be defined as a parametric surface, and the position of the point p as a function of the parametric coordinates u, v is relative to the unit square.

Where

Is a Bernstein polynomial,

Is a binomial coefficient. For details, see Grune et al., On Numerical Algorithm and Interactive Visualization for Optimal Control Problems, Journal of Computation and Visualization in Science, Vol. 1, No. 4, July 1999. This document is referred to in its entirety in this specification.

Various other surface rendering techniques are disclosed in other references. See, for example, the surface rendering techniques disclosed in the following publications:
Lorensen et al., Marching Cubes: A high Resolution 3d Surface Construction Algorithm, Computer Graphics, Vol. 21-3, pp. 163-169, 1987
Farin et al., NURB Curves & Surfaces: From Projective Geometry to Practical Use, Wellesley, 1995
Kumar et al., Robust Incremental Polygon Triangulation for Surface Rendering, WSCG, 2000
Fleischer et al., Accurate Polygon Scan Conversion Using Half-Open Intervals, Graphics Gems III, pp. 362-365, Code: pp. 599-605, 1992
Foley et al., Computer Graphics: Principles and Practice, Addison Wesley, 1990
Glassner, Principles of Digital Image Synthesis, Morgan Kaufmann, 1995. All these references are hereby incorporated by reference in their entirety.

  g. Selection of jig material having a size and / or shape that most closely resembles the size of the patient's upper tibia

  As described above, the arthroplasty jig 2, such as the tibial jig 2B, includes an inner portion 104 and an outer portion 106. The tibial jig 2B is formed from a tibial jig blank 50B, and the jig blank is selected from a finite number of tibial jig blank sizes in one embodiment. The selection of the tibial jig blank 50B compares the size and / or shape of the patient's upper tibial end 604 with various sizes of the tibial jig blank 50B, and the size and / or shape is most closely matched to the patient's upper tibial end 604. Is performed by selecting a tibial jig blank 50B similar to the above. The tibial jig blank 50B selected in this manner has an outer side, that is, an outer side surface, that is, a curved surface 632, which forms the outer portion 632 of the tibial jig 2B. The 3D surface computer model 40 described in the immediately preceding chapter of this specification is used to define the 3D curved surface 630 inside the computer model of the tibial jig blank 50B.

  Selecting a tibial jig blank 50B having an outer portion 632 that is close in size to the patient's upper tibia distal end 604 increases the likelihood of an exact alignment between the inner portion 630 and the patient's tibia. Also, the amount of material that needs to be processed or otherwise removed from the jig blank 50B is reduced, thereby reducing material waste and manufacturing time.

  To illustrate how to select the jig blank 50 that most closely corresponds to the size and / or shape of the patient's upper tibia distal end, reference is first made to FIGS. 13A-14B. FIG. 13A is a top perspective view of the left tibial cutting jig blank 50BR having a predetermined dimension. FIG. 13B is a bottom perspective view of the jig blank 50BR shown in FIG. 13A. FIG. 13C is a plan view of the outside of the jig blank 50BR shown in FIG. FIG. 14A shows a plurality of available sizes of the left tibial jig blank 50BR, each drawn from the same viewpoint as FIG. 13C. FIG. 14B is a plurality of available sizes of right tibial jig material, each drawn from the same perspective as FIG. 13C.

  A common jig blank 50, such as the right jig blank 50BR for generating a right tibia jig that can be used on the patient's right tibia shown in FIGS. 13A-13C, is a medial tibia foot that mates with the medial tibia plateau. A protrusion 648, a lateral tibial foot protrusion 650 mated with the lateral tibial plateau, a posterior edge 640, an anterior edge 642, an outer edge 644, an inner edge 646, an outer 632, and an inner 630 ,including. The jig blank 50BR of FIGS. 13A-13C may be any one of a number of right tibial jig blanks 50BR available in a limited number of standard sizes. For example, the jig material 50BR in FIGS. 13A to 13C may be an i-th right tibial jig material (where i = 1, 2, 3, 4,... M, m are the maximum number of right tibial jig material sizes).

  As shown in FIG. 13C, the front-rear surface length TAi of the jig blank 50BR is obtained by measuring the rear edge 640 from the front edge 642 of the jig blank 50BR. The inside-outside length TMi of the jig blank 50BR is measured from the outer edge 644 to the inner edge 646 of the jig blank 50BR.

As can be seen from FIG. 14A, a limited number of right tibial jig blank sizes can be selected as the right tibial jig blank size to be machined into the right tibial cutting jig 2B. For example, in one embodiment, three sizes (m = 3) of right tibia jig blank 50BR can be used. As can be seen from FIG. 13C, each tibial jig blank 50BR has an anterior-posterior / medial-lateral aspect ratio (eg, “TAi / TMi” aspect ratio) defined as TAi vs. TMi. As can be seen from FIG. 14A, the jig material 50BR-1 has an aspect ratio defined by "TA ₁ / TM ₁ ", and the jig material 50BR-2 has an aspect ratio defined by "TA ₂ / TM ₂ ". The jig material 50BR-3 has an aspect ratio defined by "TA ₃ / TM ₃ ".

  The jig blank aspect ratio is used to design the right tibial jig 2B with dimensions specific to the patient's right tibia shape. In one embodiment, the jig blank aspect ratio may be the outer dimension of the right tibial jig 2B. In another embodiment, the jig blank aspect ratio may be applied to a right tibial jig manufacturing procedure for selecting a right jig blank 50BR having parameters close to the dimensions of the desired right tibial jig 2B. This embodiment can reduce the amount of machining required to produce the desired jig 2 from the selected jig blank 50, thus improving the cost efficiency of the right tibial jig manufacturing process.

  FIG. 14A shows one jig material aspect ratio for a candidate tibial jig material size. In an embodiment with many jig blank aspect ratios for candidate tibial jig blank sizes, FIG. 14A is similar to FIG. 4A, with direction N-1 indicating that the jig aspect ratio increases, and possibly direction N-2 and N-3. The relationship between the various tibial jig blank aspect ratios will be similar to that described with respect to FIG. 4A for the femur jig blank aspect ratio.

  As can be seen from the scatter diagram 900 shown in FIG. 17 and the description of the latter part of this specification, the direction E-1 corresponds to the diagonal line connecting the group 1, group 2, and group 3 in the scatter diagram 900. To do.

As shown in FIG. 14A, the jig aspect ratio is constant between the jigs 50BR-1, 50BR-2, and 50BR-3 along the direction E-1, and "TA ₁ / TM ₁ " = "TA ₂ / TM ₂ "=" TA ₃ / TM ₃ ". However, the dimensions of 50BR-2 are larger and longer than the jig 50BR-1 compared to the jig 50BR-1. This is because the TA ₂ value of the jig 50BR-2 increases to some extent in all directions of the X, Y, and Z axes in proportion to the increase of the TM ₂ value. Similarly, since the TA ₃ value increases to some extent in all directions of the X, Y, and Z axes in proportion to the increase of the TM ₃ value, the size of 50BR-3 is larger and longer than the jig 50BR-2. . An example of an increase is an increase from 5% to 20%. As shown in FIG. 4A for the femur jig blank size, in an embodiment where there is an additional jig blank aspect ratio for the candidate tibial jig blank size, the relationship between the various tibial jig blank sizes is shown in FIGS. 4A and 14A. Would be similar to that described for.

As can be seen from FIG. 14B, a limited number of right tibial jig blank sizes can be selected as the right tibial jig blank size to be machined into the right tibial cutting jig 2B. For example, in one embodiment, three sizes (m = 3) of the left tibia jig blank 50BL can be used. As can be seen from FIG. 13C, each tibial jig blank 50BL has an anterior-posterior / medial-lateral aspect ratio (eg, “TAi / TMi” aspect ratio) defined as TAi vs. TMi. 14B, the jig material 50BL-1 has an aspect ratio defined by "TA ₁ / TM ₁ ", and the jig material 50BL-2 has an aspect ratio defined by "TA ₂ / TM ₂ ". The jig material 50BL-3 has an aspect ratio defined by “TA ₃ / TM ₃ ”.

  The jig blank aspect ratio is used to design the left tibial jig 2B with dimensions that are specific to the shape of the patient's left tibia. In one embodiment, the jig blank aspect ratio may be the outer dimension of the left tibia jig 2B. In another embodiment, the jig blank aspect ratio may be applied to a left tibia jig manufacturing procedure for selecting a left jig blank 50BL having parameters close to the desired dimensions of the left tibia jig 2B. This embodiment can reduce the amount of machining required to produce the desired jig 2 from the selected jig blank 50, thus improving the cost efficiency of the left tibial jig manufacturing process.

  FIG. 14B shows one jig material aspect ratio for a candidate tibial jig material size. In an embodiment where there are many jig blank aspect ratios for candidate tibial jig blank sizes, FIG. 14B is similar to FIG. 4B, with direction N-1 indicating that the jig aspect ratio increases, and possibly direction N-2 and N-3. The relationship between the various tibial jig blank aspect ratios will be similar to that described with respect to FIG. 4B for the femur jig blank aspect ratio.

As shown in FIG. 14B, the jig aspect ratio is constant between the jigs 50BL-1, 50BL-2, and 50BL-3 along the direction E-1, and "TA ₁ / TM ₁ " = "TA ₂ / TM ₂ "=" TA ₃ / TM ₃ ". However, compared with the jig 50BL-1, the dimension of 50BL-2 is larger and longer than the jig 50BL-1. This is because the TA ₂ value of the jig 50BL-2 increases to some extent in all directions of the X, Y, and Z axes in proportion to the increase of the TM ₂ value. Similarly, since the TA ₃ value increases to some extent in all directions of the X, Y, and Z axes in proportion to the increase in TM ₃ value, the dimension of 50BL-3 is larger and longer than the jig 50BL-2. . An example of an increase is an increase from 5% to 20%. In embodiments where there is an additional aspect ratio for the candidate tibial jig blank size, the relationship between the various tibial jig blank sizes is illustrated with respect to FIGS. 4B and 14B, as shown in FIG. 4B with respect to the femur jig blank size. It will be similar to what you did.

  The dimensions of the upper end of the patient's tibia 20, i.e., the end 604 forming the knee joint, can be determined by analyzing the 3D surface model 40, i.e., the 3D joint model 36, in a manner similar to that described for the jig blank 50. For example, as shown in FIG. 15 which is an axial view of the 3D surface model 40, or 3D joint model 36, of the patient's right tibia 20 viewed from the proximal to the distal direction, the surface model 40, ie, the joint model 36, is shown. The upper end 604 includes a front edge 660, a rear edge 662, an inner edge 664, and an outer edge 666. The tibial dimensions are measured with respect to the upper end surface of the patient's tibia 20, ie, the femoral joint sliding surface 604, by analyzing the 3D surface model 40 of the 3D joint model 36. These tibial dimensions are then used to set the tibial jig dimensions and select the appropriate tibial jig.

  As shown in FIG. 15, the upper end 604 of the patient's tibia 20 (ie, the upper end 604 of the surface model 40 of the joint model 36, whether formed by an open loop analysis or a closed loop analysis). ) Is the length measured from the front edge 660 of the tibial plateau to the back edge 662 of the tibial plateau. The medial-lateral length tML of the upper end 604 of the patient's tibia 20 is the length measured from the inner edge 664 of the medial tibial plateau to the outer edge 666 of the lateral tibial plateau.

  In one embodiment, the anterior-posterior length tAP and medial-lateral length tML of the upper tibia end 604 can be used for the aspect ratio tAP / tML of the upper tibia end. By collecting and statistically analyzing the knee aspect ratio tAP / tML of a large number of patients (eg, hundreds, thousands, tens of thousands, etc.), the most universal of jig materials that accommodate a large number of patient knees A good aspect ratio can be determined. This information can then be used to determine which one, two, three, etc. aspect ratio is likely to accommodate the maximum number of patient knees.

  The system 4 includes the patient's tibia 20 obtained by a surface model 40 of a joint model 36 (whether the joint model 36 is a 3D model generated by an open loop process or a 3D volume solid model generated by a closed loop process). The upper end 604 is analyzed to obtain data regarding the anterior-posterior length tAP and medial-lateral length tML of the upper tibia end 604. As can be seen from FIG. 16 showing the selected model jig blank 50BR of FIG. 13C superimposed on the model tibia upper end 604 of FIG. 15, the tibial dimension lengths tAP, tML are represented by the jig blank dimension lengths TA, TM and In comparison, the jig material model to be selected as the starting point of the processing and the outer surface model of the jig model is determined.

  As shown in FIG. 16, a planned right tibia jig blank 50BR is superimposed so as to mate with the upper right tibia end 604 of the patient's anatomy model represented by the surface model 40 or joint model 36. In one embodiment, the jig blank 50BR covers about 2/3 of the tibial plateau and about 1/3 of the back of the tibia remains exposed. The exposed portions of the tibial plateau include the exposed and medial portions of the tibial plateau represented by regions q1 and q2 in FIG. In particular, the exposed region q1 is a region of the exposed tibial plateau between the tibial outer edge 666 and the jig material outer edge 646, and the exposed region q2 is an area between the tibial inner edge 664 and the jig material inner edge 644. It is the area of the exposed tibial plateau.

By acquiring and using the tibial anterior-posterior tAP data and medial-lateral tML data, the system 4 can change the size of the tibial jig blank 50BR according to the following formula:
jTML = tML-q1-q2
Here, jTML is the medial-lateral length of the tibial jig blank 50BR. In one embodiment, q1 and q2 are in the following ranges.
2mm ≤ q1 ≤ 4mm, 2mm ≤ q2 ≤ 4mm
In another embodiment, q1 is about 3 mm and q2 is about 3 mm.

  FIG. 17A is an exemplary scatter plot 900 for selecting a jig material size suitable for the upper end 604 of the patient's tibia 20 from a plurality of candidate jig material sizes. In one embodiment, the X-axis represents the patient's medial-lateral length tML in millimeters and the Y-axis represents the patient's anterior-tibial length tAP in millimeters. In one embodiment, the scatter diagram 900 is divided into several jig material size groups, each group containing one region of the scatter diagram 900 and associated with a specific parameter TMr for a specific candidate jig material size.

  In one embodiment, the example scatter diagram 900 shown in FIG. 17A includes three material size groups, each group belonging to one candidate jig material size. However, depending on the embodiment, the scatter plot 900 may include more jig material size groups or fewer jig material size groups. The greater the number of jig material size groups, the greater the number of candidate jig material sizes, and the selected candidate jig material size will be more specific to the patient's knee shape and the resulting jig 2. As the selected candidate jig blank size is more dimensionally specified, the amount of machining required to manufacture the desired jig 2 from the selected candidate jig blank 50 is reduced.

  Conversely, the smaller the number of jig material size groups, the smaller the number of candidate jig material sizes, and the selected candidate jig material size will not be dimension specific due to the patient's knee shape and the resulting jig 2. The more the selected candidate jig blank size is more dimensionally specified, the more machining is required to produce the desired jig 2 from the selected candidate jig blank 50, and extra roughing in the jig manufacturing procedure. Will increase.

The tibial anterior-posterior length tAP may be relevant because it is used as a value to determine the aspect ratio TA _i / TM _i of the tibial jig blank 50B as described with respect to FIGS. 13C-14B and 17A. Nevertheless, in some embodiments, the anterior tibia length TA _i of the candidate jig material is the tibia anterior posterior length in the practical setting in some embodiments. Since it is less important than the jig inner-outer length, it may not be reflected in the scatter plot 900 shown in FIG. 17A or the relationship shown in FIG. For example, the patient's anterior-posterior tibial distance varies depending on the knee shape, but the length of the foot processes 800, 802 (see FIG. 20A) of the tibia jig 2B is simply increased to an anterior-tibia length TA. There is no need to generate a jig material or jig that is specialized to correspond. In other words, in some embodiments, the only difference in anterior-posterior length between the various tibial jigs is the anterior-posterior length difference of the corresponding foot process 800, 802.

  In some embodiments, as can be seen in FIGS. 16 and 21, the anterior-posterior length of the tibial jig 2B with foot processes 800, 802 spans about half of the tibial plateau. Due to the inclusion of this “half” distance, which varies from only a few millimeters to a few centimeters for each patient, in part, the anterior-posterior length of the jig is not critical in one embodiment. However, since the jig may span most of the medial-lateral length of the tibial plateau, the medial-lateral length of the jig is very important compared to the anterior-posterior length.

In some embodiments, the anterior-posterior length of the tibial jig 2B may not be very important compared to the medial-lateral length, but in some embodiments, the anterior portion of the tibial jig -Rear length is important. In such an embodiment, the jig size may be shown in FIG. 17A not only by TM _i but also by aspect ratio TA _i / TM _i . In other words, the jig size may be shown in FIG. 17A in a manner similar to that shown in FIG. 7A. Further, in some embodiments, FIGS. 14A and 14B include additional jig blank aspect ratios similar to those shown in FIGS. 4A and 4B. As a result, the scatter plot 900 of FIG. 17A may include additional diagonal lines connecting the jig blank sizes for each jig blank aspect ratio in a manner similar to that shown in the scatter plot 300 of FIG. 7A. In FIG. 17A, additional horizontal lines may be provided that divide the scatter plot 900 by front-rear length to represent the boundaries of various jig blank sizes in a manner similar to that shown in FIG. 7A. .

As can be seen from FIG. 17A, in one embodiment, the three jig material size groups in the scatter diagram 900 have the following parameters TMr, TAr. Group 1 has parameters TM ₁ and TA ₁ . TM ₁ represents the medial-lateral length of the first tibial jig blank size, TM ₁ = 70 mm. TA ₁ represents the anterior-posterior length of the first tibial jig blank size, TA ₁ = 62 mm. Group 1 includes tibial tML and tAP data for patients with a range of 55 mm <tML <70 mm and 45 mm <tAP <75 mm.

Group 2 has parameters TM ₂ and TA ₂ . TM ₂ represents the medial-lateral length of the second tibial jig blank size, TM ₂ = 85mm. TA ₂ represents the anterior-posterior length of the second tibial jig blank size, TA ₂ = 65 mm. Group 2 includes tibial tML and tAP data for patients with a range of 70 mm <tML <85 mm and 45 mm <tAP <75 mm.

Group 3 has parameters TM ₃ and TA ₃ . TM ₃ represents the medial-lateral length of the third tibial jig blank size, TM ₃ = 100 mm. TA ₃ represents the anterior-posterior length of the third tibial jig blank size, TA ₃ = 68.5 mm. Group 3 includes patient tibial tML and tAP data in the range of 85 mm <tML <100 mm and 45 mm <tAP <75 mm.

  In some embodiments, unlike the femur jig blank selection process described with respect to FIGS. 3A-7B, the tibial jig blank selection process described with respect to FIGS. 13A-17B may be associated with the medial-lateral tibial jig value jTML. Only the inner-outer values TM, tML may be considered or used. Thus, in some embodiments, the anterior-posterior tibial jig value jTAP and the associated anterior-posterior values TA, tAP of the tibial jig and the tibial plateau are not considered.

  As can be seen from FIG. 17B, which is a flowchart illustrating an example process for selecting an appropriately sized jig blank, the medial-lateral length tML of the bone is measured with respect to the upper end 604 of the surface model 40 of the joint model 36. (Block 3000). The medial-lateral length tML of the upper end 604 is mathematically modified by the jTML formula described above to become the minimum tibial jig blank medial-lateral length jTML (block 3010). The mathematically modified medial-lateral tML of the bone, or more specifically, the minimum tibial jig blank medial-lateral length jTML is referenced to the jig blank dimensions of the scatter plot 900 of FIG. 17A (block 3020). ). The scatter diagram 900 can graphically represent the lengths of candidate tibial jig materials that form the jig material library. The tibial jig blank 50B is selected to have a jig blank size that has a minimum length that is still large enough to accommodate the minimum tibial jig blank medial-lateral length jTML (block 3030).

  In one embodiment, the outside of the selected jig blank size is used as the outer surface model of the jig model, as will be described below. In one embodiment, the selected jig blank size is placed on a CNC machine and trimmed to the minimum tibial jig blank anterior-posterior length jTAP and medial-lateral length jTML, and on the outer surface of the tibial jig 2B. Corresponds to actual jig material that has been machined or otherwise formed.

The method outlined in FIG. 17B and related to the scatter plot 900 of FIG. 17A can be further understood by the following example. In FIG. 16 for the upper end 604 of the patient's tibia 20, the measured patient's tibia length is as follows: tML = 85.2mm (block 3000). As described above, the upper end 604 may be part of the surface model 40 of the joint model 36. Once the tML measurement is measured from the upper end 604, the corresponding jig jTML data can be determined by the above jTML formula as follows (block 3010).
jTML = tML -q1-q2, where q1 = 3mm, q2 = 3mm
The calculation result by jTML formula is jTML = 79.2mm.

As can be seen from the scatter diagram 900 of FIG. 17A, the measured jig data (ie, jTML = 79.2 mm) is included in group 2 of the scatter diagram 900. Group 2 has a predetermined tibial jig blank parameter (TM ₂ ), ie TM ₂ = 85 mm. This predetermined tibial jig blank parameter is the smallest of the various groups, but is still large enough for the minimum tibial blank length jTML. (Block 3020). This predetermined tibial jig blank parameter (TM ₂ = 85 mm) may be selected as an appropriate tibial jig blank size (block 3030).

  In one embodiment, a predetermined tibial jig blank parameter (85 mm) may be applied to the outer tibial jig dimensions as shown in FIG. 13C. In other words, the jig blank outer portion is used as the jig model outer portion as described with reference to FIGS. Accordingly, the outer portion of the tibial jig blank 50B may not be machined, and the unmodified outer portion of the jig blank 50B having a predetermined jig blank parameter (85 mm) may be used as the outer portion of the completed tibial jig 2B. it can.

  In another embodiment, the tibial jig blank parameter (85 mm) may be selected for machining jig manufacture. Therefore, the tibial jig blank 50B having a predetermined parameter (85mm) is supplied to the machining process, and the outer portion of the tibial jig blank 50B is processed from the predetermined parameter (85mm) to a desired tibial jig parameter (79.2mm). This is the completed outer part of the jig 2B. By selecting the predetermined parameter (85mm) relatively close to the desired tibial jig parameter (79.2mm), processing time and material waste are reduced.

  To reduce processing time and material waste, it is advantageous to use the jig material selection method described above, but in some embodiments, the jig material is simply applicable to all patient bone lengths tML. A large enough thing is provided. Such a jig material is processed into a desired jig material length jTML and used as the outer surface of the completed jig 2B.

  In one embodiment, the number of candidate jig material size groups represented in the scatter diagram 900 is a function of the number of jig material sizes provided by the jig material manufacturer. For example, the first scatter diagram 900 pertains only to jig materials manufactured by Company A that provides three types of jig material sizes. Accordingly, the scatter diagram 900 has three jig material size groups. The second scatter diagram 900 pertains only to jig materials manufactured by Company B that provides six different jig material sizes. Accordingly, the scatter diagram 900 has six jig material size groups.

  As shown in the scatter diagram 900 of FIG. 17A, for example, the jig material library has a plurality of candidate jig material sizes. Each candidate jig material may have a unique combination of front-rear dimension size and inner-outer dimension size, but two or more candidate jig materials have a common aspect ratio tAP / tML, ie, shape. You may share. The candidate jig materials in the library are grouped along the oblique line of the scatter diagram 900 according to the aspect ratio tAP / tML.

  In one embodiment, the jig material aspect ratio tAP / tML may be used to select a jig material shape that can be machined and machine it to fit a larger or smaller individual.

  As can be seen from FIG. 17A, as part of the tibial jig design study, 98 osteoarthritis patients with knee injuries were entered into the scatter plot 900. The tibial tAP and tML data for each patient was measured. The tibial tML data of each patient was corrected by the above-mentioned jTML formula to become patient jig material data (jTML). The patient's jig material data was entered as points in the scatter diagram 900. As can be seen from FIG. 17A, there are no patient points other than the available group parameters. Such a process can be used to set the group parameters and the number of groups required.

  In one embodiment, the selected jig blank parameter may be a tibial jig outer dimension specific to the patient's knee shape. In another embodiment, the selected jig blank parameters may be selected during the manufacturing process.

  h. Formation of 3D tibial jig model

  To illustrate an example of a method for generating a 3D tibial jig model 746 that roughly corresponds to the “integrated jig data” 48 described for block 150 of FIG. 1E, FIGS. 13A-13C, 18A-18B, 19A-19D, Reference is made to 20A-20B. 13A-13C are various views of the tibial jig blank 50B. 18A to 18B are an outer perspective view and an inner perspective view of the tibial jig blank outer surface model 632M, respectively. FIGS. 19A-19D are outer perspective views of the combined tibial jig blank outer surface model 632M and bone surface model 40, respectively. FIGS. 20A and 20B each integrate “saw cutting and drilling data” 44 into the jig model 746, resulting in an integrated jig model or full jig model 748 that generally corresponds to the “integrated jig data” 48 described with respect to block 150 of FIG. 1E. FIG. 6 is a lateral and medial perspective view of the resulting tibial jig model 746 after

  As can be seen in FIGS. 13A-13C, a jig blank 50B having the selected predetermined dimensions described with respect to FIGS. 17A and 17B includes an inner surface 630 and an outer surface 632. The outer surface model 632M shown in FIGS. 18A and 18B is extracted from or otherwise generated from the outer surface 632 of the jig blank model 50B. Accordingly, the outer surface model 632M is based on the jig material aspect ratio of the selected tibial jig material 50B as described with respect to FIGS. 17A and 17B and has dimensions specific to the patient's knee shape. The tibial jig surface model 632M can be extracted or otherwise generated from the jig blank model 50B of FIGS. 13A-13C using any of the computer surface rendering techniques described above.

  As can be seen from FIGS. 19A-19C, the outer surface model 632M is combined with the tibial surface model 40 to form the outer and inner surfaces of the tibial jig model 746, respectively. The tibial surface model 40 represents the inner surface of the tibial jig 2B, that is, the capturing surface, and corresponds to the tibial arthroplasty target region 42. In this way, the model 40 allows the obtained tibial jig 2B to be indexed to the arthroplasty target area 42 of the patient's tibia 20 and the tibial jig 2B obtained thereby is subjected to arthroplasty during the arthroplasty procedure. The target area 42 is captured. The two surface models 632M, 40 are combined into a patient-specific jig model 746 for manufacturing the tibial jig 2B.

  As can be seen from FIGS. 19B and 19C, when the models 632M, 40 are properly aligned, a gap is created between the two models 632M, 40. The prepared models 632M and 40 are subjected to an image stitching method, that is, an image stitching tool, to combine the two surface models into one, and the 3D computer generated jig model 746 of FIG. 19B is combined with the integrated jig model 748 shown in FIGS. 20A and 20B. The jig model 746 is a single unit having a similar appearance, joined together, and filled with a gap. In one embodiment, the jig model 746 may generally correspond to the description of “jig data” 46 described with respect to block 145 of FIG. 1E.

As can be seen from FIGS. 19B-19D and FIGS. 20A and 20B, the geometric gap between the two models 632M, 40, some of which are described below for thicknesses V ₁ , V ₂ and V ₃ , TKA surgery A certain space can be provided between the two models 632M, 40 due to the width and length of the slot that accepts and guides the cutting instrument during drilling, and the length of the drill bit. Since the resulting tibial jig model 748 shown in FIGS. 20A and 20B may be a 3D volume model generated from the 3D surface models 632M, 40, a space or gap is provided between the 3D surface models 632M, 40. The resulting 3D volume jig model 748 can be used to generate an actual physical 3D volume tibial jig 2B.

In some embodiments, the image processing procedure may include a model modification procedure that modifies the jig model 746 after alignment of the two models 632M, 40. For example, without limitation, various methods of model modification include user-guided correction, crack identification and filling, and manifold connectivity generation as described in the following literature: Including.
Nooruddin et al., Simplification and Repair of Polygonal Models Using Volumetric Techniques, IEEE Trans. On Visualization and Computer Graphics, Vol. 9, No. 2, April-June 2003
Erikson, C., Error Correction of a large Architectural Model: The Henderson County Courthouse, Technical Report TR95-013, Dept. of Computer Science, Univ. Of North Carolina at Chapel Hill, 1995
Khorramabdi, D., A Walk through the Planned CS Building, Technical Report UCB / CSD 91/652, Computer Science Dept., Univ. Of California at Berkeley, 1991
Morvan et al., IVECS: An Interactive Virtual Environment for the Correction of .STL files, Proc. Conf. Virtual Design, August 1996
Bohn et al., A Topology-Based Approach for Shell-Closure, Geometric Modeling for Product Realization, PR Wilson et al., Pp. 297-319, North-Holland, 1993
Barequet et al., Filling Gaps in the Boundary of a Polyhedron, Computer Aided Geometric Design, Vol. 12, No. 2, pp.207-229, 1995
Barequet et al., Repairing CAD Models, Proc. IEEE Visualization '97, pp. 363-370, October 1997
Gueziec et al., Converting Sets of Polygons to Manifold Surfaces by Cutting and Stitching, Proc. IEEE Visualization '98, pp. 383-390, October 1998, all of which are incorporated herein in their entirety.

As can be seen from FIGS. 20A and 20B, the integrated jig model 748 may include several features as desired by the surgeon. For example, the jig model 748 may include a slot 30 for receiving and guiding a bone saw and a drill hole 32 for receiving and guiding a bone drill bit. As can be seen from FIGS. 19B and 19C, the tibial jig 2B obtained is sufficiently structured to properly support and guide the bone saw and drill bit without being distorted or deformed during the arthroplasty procedure. The gap between models 632M, 40 may have the following offsets V ₁ , V _2, and V _{3 so as} to have overall integrity.

As can be seen from FIGS. 19B-20B, in one embodiment, the thickness V ₁ extends along the length of the front drill hole 32P between the models 632M, 40 and is received during the arthroplasty procedure. Support and guide. The thickness V ₁ may be at least about 4 mm or at least about 5 mm. The diameter of the front drill hole 32P may be configured to receive a cutting instrument having a diameter of at least 1/3 inch.

The thickness V ₂ is the thickness of the jig legs 800 and 802 between the inner surface 40 and the outer surface model 632M. This thickness provides adequate structural strength of the jig legs 800, 802 to resist jig distortion and deformation during manufacture and use. The thickness V ₂ may be at least about 5 mm or at least about 8 mm thick.

The thickness V ₃ extends along the length of the saw slot 30 between the models 632M, 40 to support and guide the bone saw received during the arthroplasty procedure. The thickness V ₃ may be at least about 10 mm or at least about 15 mm.

In addition to providing a sufficiently long surface to guide the received drill bit or saw, various thicknesses V ₁ , V ₂ and V ₃ can be used to cut and drill the tibia when the tibial jig 2B is undergoing TKR surgery. , Structurally designed to withstand the powerful treatment of punching holes.

As shown in FIGS. 20A and 20B, the outer portion of the integrated jig model 748, ie, the outer 106, includes:
A shape 800 that covers and matches the inside of the patient's tibial plateau
A shape 802 that covers and matches the outside of the patient's tibial plateau
A protrusion 804 extending downward from the upper outer surface 632 of the jig 2B
The flat portion of the outer surface 632 that provides a blank label area listing information relating to the patient, surgeon and / or surgical procedure. As discussed above, the integrated jig model 748 may also include the saw cutting slot 30 and the drill hole 32. The inner or inner 104 (and resulting tibial jig 2B) of the jig model 748 is a tibial surface model 40 that captures the arthroplasty area 42 of the patient's tibia 20 during the arthroplasty procedure.

  As can be seen with reference to block 105 of FIG. 1B and FIGS. 12A-12C, in one embodiment, when the models 40, 22 are generated by accumulating the image scan data 16, the models 40, 22 have a point P. Reference to point P may be a single point, a series of points, etc. that refer to and direct models 40, 22 to models 22, 28 used in the POP as described with respect to FIG. 1C. Any change reflected in the models 22 and 28 for the point P due to the POP (eg, the point P becomes the point P ′) is reflected in the point P related to the models 40 and 22 (FIG. 1D). (See block 135). Thus, as can be seen from block 140 of FIG. 1D and FIGS. 19A-19C, when the jig blank outer surface model 632M is combined with the surface model 40 (ie, a surface model made from the joint model 22) to generate the jig model 746. , Jig model 746 is referenced and oriented to point P ′ and is roughly equivalent to “Jig data” 46 described with respect to block 145 of FIG. 1E.

  Since the jig model 746 is appropriately referenced and oriented with respect to the point P ′, the “saw cutting and drilling data” 44 described with respect to block 125 of FIG. 1E is appropriately integrated into the jig model 746 to produce FIG. The integrated jig model 748 shown in FIG. The integrated jig model 748 includes a sawing slot 30, a drill hole 32, and a surface model 40. Accordingly, the integrated jig model 748 is roughly equivalent to the “integrated jig data” 48 described in block 150 of FIG. 1E.

  As can be seen from FIG. 21, which is a perspective view of the integrated jig model 748 mating with the “joint model” 22, the inner surface 40 of the jig model 748 captures the arthroplasty target region 42 of the lower tibial end 604, and thereby the jig model. 748 is indexed to mate with the region 42. By referencing and orienting various models to points P, P ′ throughout the procedure, the sawing slot 30 and drill hole 32 allow the resulting tibial jig 2B to restore the patient's joint to its pre-degenerative state. Properly oriented for sawing and drilling.

  As shown in FIG. 21, the integrated jig model 748 includes a jig body 850, a projection 852 covering the medial tibial plateau, a projection 854 covering the lateral tibial plateau, a lower portion 856 extending from the body 850, a rear drill hole 32P, , Front drill hole 32A, saw slot 30, and upper flat 856 for receiving patient, surgery, and physician data. The protrusions 852, 854 extend over the corresponding medial and lateral tibial plateaus. The protrusions 852, 854, 856 extend integrally from the jig body 850.

  As can be seen from blocks 155-165 of FIG. 1E, the integrated jig 748, or more specifically integrated jig data 48, can be sent to the CNC machine 10 to machine the tibial jig 2B from the selected jig blank 50B. . For example, the integrated jig data 48 may be used to create a production file that provides automatic jig manufacturing instructions to the high speed production machine 10 as described in the various Park patent applications referenced above. Then, the high-speed production machine 10 manufactures the arthroplasty tibial jig 2B specialized for the patient from the tibial jig material 50B according to the instruction.

  The resulting tibial jig 2B may have the shape of the integrated jig model 748. Thus, as can be seen from FIG. 21, the resulting tibial jig 2B may have a slot 30 and a drill hole 32 formed on the protrusions 852, 854, 856, as desired by the surgeon. The drill hole 30 prevents IR / ER (inside / outside) rotational axis misalignment that may occur between the tibial cutting jig 2B and the patient's damaged joint surface during TKR proximal tibia cutting Can be opened. The slot 30 is opened to accept a cutting instrument such as a reciprocating saw blade for transverse cutting during a TKR proximal tibial cut.

  Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims (60)

A method of manufacturing an arthroplasty jig,
Generating a two-dimensional image of at least a portion of the bone forming the joint;
Generating a first three-dimensional computer model of at least a portion of the bone from the two-dimensional image;
Generating a second three-dimensional computer model of at least a portion of the bone from the two-dimensional image;
The step of causing the first three-dimensional computer model and the second three-dimensional computer model to have a common reference position, wherein the reference position includes at least one of a position and a direction with respect to an origin. Steps,
Generating first type data using the first three-dimensional computer model;
Generating second type data using the second three-dimensional computer model;
Integrating the first type data and the second type data into integrated jig data using the reference position;
Using the integrated jig data to manufacture the arthroplasty jig on a manufacturing machine;
Having a method.   The method according to claim 1, wherein the first three-dimensional computer model is a bone-only model, and the second three-dimensional computer model is a bone and cartilage model.   The method of claim 2, wherein the bone-only model and the bone and cartilage model represent a degenerated state of the joint.   The first three-dimensional computer model represents an approximation of at least a portion of the bone in the degenerated state, and the second three-dimensional computer model represents at least a portion of the bone and a degenerated cartilage. The method according to 1.   The method of claim 1, wherein the first type data includes at least one of sawing information and drilling information, and the second type data includes curved surface contour information of at least a part of the bone.   6. The method of claim 5, wherein the sawing information and drilling information includes at least one of a position, direction, and dimension for at least one of the proposed arthroplasty sawing and drilling.   The method of claim 1, wherein the second three-dimensional computer model is generated at least in part from an open loop contour derived at least in part from the two-dimensional image.   The method of claim 1, wherein the second 3D computer model is generated at least in part from a closed loop contour derived at least in part from the 2D image.   The method according to claim 1, wherein the first three-dimensional computer model is a three-dimensional volume model.   The method according to claim 1, wherein the second three-dimensional computer model is a three-dimensional surface model.   The method of claim 1, wherein the two-dimensional image is an MRI image.   The method of claim 1, wherein the two-dimensional image is a CT image.   The method according to claim 1, wherein the reference position is at least one of a point, a plurality of points, a vector, a plane, a plane, and a point.   The method according to claim 1, wherein the reference position is in the vicinity of the joint in the two-dimensional image.   The method according to claim 1, wherein the joint is at least one of a joint of a knee, an elbow, a hand, a foot, a shoulder, a waist, and a spine.   The method according to claim 1, wherein the change in the position and direction of each of the three-dimensional computer models with respect to one origin causes an equal change in the position and direction of each of the three-dimensional computer models with respect to the other origin. Comparing the dimensions of at least a portion of the bone with a candidate jig blank;
Selecting from the candidate jig material a jig material having a minimum dimension capable of accommodating at least a part of the bone;
Supplying the selected jig material to the manufacturing machine;
The method of claim 1 further comprising: Mathematically modifying the dimensions of at least a portion of the bone;
Determining which candidate jig material to select using the mathematically modified dimensions;
18. The method of claim 17, further comprising:   The method of claim 17, wherein a dimension of at least a portion of the bone is obtained from at least one of the two-dimensional image and the three-dimensional computer model.   An arthroplasty jig produced by the method of claim 1. A method of manufacturing an arthroplasty jig,
Generating a two-dimensional image of at least a portion of the bone forming the joint;
Extending at least some of the two-dimensional images an open-loop contour along the arthroplasty site;
Generating a three-dimensional computer model of the arthroplasty site from the open loop contour line;
Generating curved surface contour data belonging to the arthroplasty site from the three-dimensional computer model;
Manufacturing the arthroplasty jig on a manufacturing machine using the curved surface contour data;
Having a method.   The method according to claim 21, wherein the three-dimensional computer model is a bone and cartilage model.   23. The method of claim 22, wherein the bone and cartilage model represents a degenerated state of the joint.   The method of claim 21, wherein the second three-dimensional computer model is a three-dimensional surface model.   The method of claim 21, wherein the two-dimensional image is an MRI image.   The method of claim 21, wherein the two-dimensional image is a CT image.   The method according to claim 21, wherein the joint is at least one of a joint of a knee, an elbow, a hand, a foot, a shoulder, a waist, and a spine. Comparing the dimensions of at least a portion of the bone with a candidate jig blank;
Selecting from the candidate jig material a jig material having a minimum dimension capable of accommodating at least a part of the bone;
Supplying the selected jig material to the manufacturing machine;
The method of claim 21, further comprising: Mathematically modifying the dimensions of at least a portion of the bone;
Determining which candidate jig material to select using the mathematically modified dimensions;
The method of claim 28, further comprising:   30. The method of claim 29, wherein a dimension of at least a portion of the bone is obtained from at least one of the two-dimensional image and the three-dimensional computer model.   The method of claim 21, wherein the open loop contour extends to cortical bone and cartilage directly adjacent to the arthroplasty site.   An arthroplasty jig manufactured by the method of claim 21. A computer-generated method for generating a three-dimensional surface model of an arthroplasty target part of a bone forming a joint,
Generating a two-dimensional image of at least a portion of the bone;
Generating an open loop contour along the arthroplasty site in at least some of the two-dimensional images;
Generating a three-dimensional model of the arthroplasty site from the open loop contour;
Having a method.   34. The method of claim 33, wherein the three-dimensional model is a bone and cartilage model.   35. The method of claim 34, wherein the bone and cartilage model represents a degenerated state of the joint.   34. The method of claim 33, wherein the two-dimensional image is an MRI image.   34. The method of claim 33, wherein the two-dimensional image is a CT image.   The method according to claim 33, wherein the joint is at least one of a joint of a knee, an elbow, a hand, a foot, a shoulder, a waist, and a spine.   34. The method of claim 33, wherein the open loop contour extends to cortical bone and cartilage directly adjacent to the arthroplasty site. A method of manufacturing an arthroplasty jig,
Determining from the image at least one dimension related to a portion of the bone;
Comparing the at least one dimension with the dimensions of at least two candidate jig blank sizes;
Selecting the smallest jig blank size that can accommodate the at least one dimension;
Supplying the selected size jig material to a manufacturing machine;
Producing the arthroplasty jig from the jig material;
A method further comprising:   41. The method of claim 40, wherein the image is a two-dimensional MRI image.   41. The method of claim 40, wherein the image is a two-dimensional CT image.   41. The method of claim 40, wherein the image is a 3D computer generated surface model.   41. The method of claim 40, wherein the image is a three-dimensional computer generated volume model.   41. The method of claim 40, wherein the at least one dimension is a length from the anterior surface to the posterior surface of the femoral arthroplasty site.   41. The method of claim 40, wherein the at least one dimension is a length from the inside to the outside of the femoral arthroplasty site.   41. The method according to claim 40, wherein the at least one dimension is a length from the inside to the outside of the tibial arthroplasty site.   Measuring at least one dimension related to a portion of the bone from an image (1) and comparing the at least one dimension with at least two candidate jig blank sizes (2); 41. The method of claim 40, further comprising mathematically modifying the at least some of the dimensions and using the mathematically modified dimensions for the comparison.   41. An arthroplasty jig produced by the method of claim 40. A method for generating a computer model of a three-dimensional arthroplasty jig,
Comparing the dimensions of at least a portion of the joint bone with the dimensions of the candidate jig blank size;
Selecting from the candidate jig material size a minimum jig material size capable of accommodating at least a portion of the bone dimensions;
Having a method.   51. The method of claim 50, further comprising forming an outer three-dimensional surface model from an outer surface of the smallest jig blank size model. Forming an inner three-dimensional surface model from at least a portion of the bone for arthroplasty;
Combining the outer surface model and the inner surface model to form an outer surface and an inner surface of the three-dimensional arthroplasty jig computer model,
52. The method of claim 51, further comprising: A method of generating a 3D arthroplasty jig computer model,
Forming an inner 3D surface model representing an arthroplasty site of at least a portion of the bone;
Forming an outer 3D surface model representing the outer surface of the jig material;
Combining the inner surface model and the outer surface model to form an inner surface and an outer surface of the three-dimensional arthroplasty jig computer model, respectively;
Having a method.   54. The method of claim 53, wherein the inner surface model and the outer surface model are spaced from each other when joined.   55. The method of claim 54, further comprising connecting the inner surface model and the outer surface model.   The method according to claim 55, wherein the connection process outputs a three-dimensional volume model of the three-dimensional arthroplasty jig computer model. A method for generating a production file related to the manufacture of an arthroplasty jig,
Generating first data relating to the curved contour of the arthroplasty site of the joint bone;
Generating second data related to at least one of sawing and drilling performed on the arthroplasty target site in the course of an arthroplasty procedure;
Integrating the first data and the second data;
Have
A method in which the positional relationship of the first data with respect to the origin and the positional relationship of the second data with respect to the origin are approximately matched with each other during the generation of the first data and the second data.   The method according to claim 57, wherein the positional relationship includes at least one of a position and a direction with respect to the origin. Generating a two-dimensional image of the bone;
Computer-generating a three-dimensional model of the bone from the two-dimensional image;
Setting a positional relationship between the first data and the second data with respect to the origin from a relationship between at least one of the two-dimensional images with respect to the origin and the three-dimensional model;
58. The method of claim 57, further comprising:   58. The method of claim 57, wherein the articular bone is part of a knee, elbow, waist, shoulder, hand, foot or spine junction.

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